Systems and methods for controlling motor velocity of a surgical stapling and cutting instrument according to articulation angle of end effector

ABSTRACT

A motorized surgical instrument is disclosed. The surgical instrument includes a displacement member, a motor, a control circuit, and a position sensor. The displacement member is configured to translate. The motor is coupled to the displacement member to translate the displacement member. The control circuit is coupled to the motor. A position sensor is coupled to the control circuit. The position sensor is configured to measure the position of the displacement member and to measure an articulation angle of an end effector relative to a longitudinally extending shaft. The control circuit is configured to determine the articulation angle between the end effector and the longitudinally extending shaft and set motor velocity based on the articulation angle.

RELATED APPLICATIONS

The present application is a continuation under 37 C.F.R. § 1.53(b) ofU.S. patent application Ser. No. 15/628,050 filed Jun. 20, 2017, nowU.S. Pat. No. ______, the entire disclosure of which is incorporated byreference herein.

TECHNICAL FIELD

The present disclosure relates to surgical instruments and, in variouscircumstances, to surgical stapling and cutting instruments and staplecartridges therefor that are designed to staple and cut tissue.

BACKGROUND

In a motorized surgical stapling and cutting instrument it may be usefulto control the velocity of a cutting member or to control thearticulation velocity of an end effector. Velocity of a displacementmember may be determined by measuring elapsed time at predeterminedposition intervals of the displacement member or measuring the positionof the displacement member at predetermined time intervals. The controlmay be open loop or closed loop. Such measurements may be useful toevaluate tissue conditions such as tissue thickness and adjust thevelocity of the cutting member during a firing stroke to account for thetissue conditions. Tissue thickness may be determined by comparingexpected velocity of the cutting member to the actual velocity of thecutting member. In some situations, it may be useful to articulate theend effector at a constant articulation velocity. In other situations,it may be useful to drive the end effector at a different articulationvelocity than a default articulation velocity at one or more regionswithin a sweep range of the end effector.

During use of a motorized surgical stapling and cutting instrument it ispossible that the force to fire or load experienced by the cuttingmember or the firing member will vary or increase based on thearticulation angle of the end effector. Therefore, it may be desirableto vary the firing velocity the cutting member or the firing member as afunction of articulation angle of the end effector to reduce the forceto fire load on the cutting member or the firing member due as afunction of increasing end effector articulation angle.

SUMMARY

In one aspect, the present disclosure provides a surgical instrument.The surgical instrument comprises a displacement member configured totranslate; a motor coupled to a proximal end of the displacement memberto translate the displacement member; a control circuit coupled to themotor; a position sensor coupled to the control circuit, the positionsensor configured to measure the position of the displacement member andconfigured to measure an articulation angle of an end effector relativeto a longitudinally extending shaft; wherein the control circuit isconfigured to: determine the articulation angle between the end effectorand the longitudinally extending shaft; select a force threshold basedon the articulation angle; set motor velocity based on the articulationangle; determine force on the displacement member; and adjust the motorvelocity when the force on the displacement member is greater than theforce threshold.

In another aspect, the surgical instrument comprises: a displacementmember configured to translate; a motor coupled to the displacementmember to translate the displacement member; a control circuit coupledto the motor; a position sensor coupled to the control circuit, theposition sensor configured to measure a position of the displacementmember relative to an end effector and configured to measure anarticulation angle of the end effector relative to the longitudinallyextending shaft; wherein the control circuit is configured to: determinearticulation angle between the end effector and the a longitudinallyextending shaft; and set motor velocity based on the articulation angle.

In another aspect, the present disclosure provides a method ofcontrolling motor velocity in a surgical instrument, the surgicalinstrument comprising a displacement member configured to translate, amotor coupled to the displacement member to translate the displacementmember, a control circuit coupled to the motor, and a position sensorcoupled to the control circuit, the position sensor configured tomeasure the position of the displacement member and configured tomeasure an articulation angle of an end effector relative to alongitudinally extending shaft, the method comprising: determining, bythe control circuit, an articulation angle between the end effector andthe a longitudinally extending shaft; and setting, by the controlcircuit, motor velocity based on the articulation angle.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the aspects described herein are set forth withparticularity in the appended claims. These aspects, however, both as toorganization and methods of operation may be better understood byreference to the following description, taken in conjunction with theaccompanying drawings.

FIG. 1 is a perspective view of a surgical instrument that has aninterchangeable shaft assembly operably coupled thereto according to oneaspect of this disclosure.

FIG. 2 is an exploded assembly view of a portion of the surgicalinstrument of FIG. 1 according to one aspect of this disclosure.

FIG. 3 is an exploded assembly view of portions of the interchangeableshaft assembly according to one aspect of this disclosure.

FIG. 4 is an exploded view of an end effector of the surgical instrumentof FIG. 1 according to one aspect of this disclosure.

FIGS. 5A-5B is a block diagram of a control circuit of the surgicalinstrument of FIG. 1 spanning two drawing sheets according to one aspectof this disclosure.

FIG. 6 is a block diagram of the control circuit of the surgicalinstrument of FIG. 1 illustrating interfaces between the handleassembly, the power assembly, and the handle assembly and theinterchangeable shaft assembly according to one aspect of thisdisclosure.

FIG. 7 illustrates a control circuit configured to control aspects ofthe surgical instrument of FIG. 1 according to one aspect of thisdisclosure.

FIG. 8 illustrates a combinational logic circuit configured to controlaspects of the surgical instrument of FIG. 1 according to one aspect ofthis disclosure.

FIG. 9 illustrates a sequential logic circuit configured to controlaspects of the surgical instrument of FIG. 1 according to one aspect ofthis disclosure.

FIG. 10 is a diagram of an absolute positioning system of the surgicalinstrument of FIG. 1 where the absolute positioning system comprises acontrolled motor drive circuit arrangement comprising a sensorarrangement according to one aspect of this disclosure.

FIG. 11 is an exploded perspective view of the sensor arrangement for anabsolute positioning system showing a control circuit board assembly andthe relative alignment of the elements of the sensor arrangementaccording to one aspect of this disclosure.

FIG. 12 is a diagram of a position sensor comprising a magnetic rotaryabsolute positioning system according to one aspect of this disclosure.

FIG. 13 is a section view of an end effector of the surgical instrumentof FIG. 1 showing a firing member stroke relative to tissue graspedwithin the end effector according to one aspect of this disclosure.

FIG. 14 illustrates a block diagram of a surgical instrument programmedto control distal translation of a displacement member according to oneaspect of this disclosure.

FIG. 15 illustrates a diagram plotting two example displacement memberstrokes executed according to one aspect of this disclosure.

FIG. 16 is a partial perspective view of a portion of an end effector ofa surgical instrument showing an elongate shaft assembly in anunarticulated orientation with portions thereof omitted for clarity,according to one aspect of this disclosure.

FIG. 17 is another perspective view of the end effector of FIG. 16showing the elongate shaft assembly an unarticulated orientation,according to one aspect of this disclosure.

FIG. 18 is an exploded assembly perspective view of the end effector ofFIG. 16 showing the elongate shaft assembly aspect, according to oneaspect of this disclosure.

FIG. 19 is a top view of the end effector of FIG. 16 showing theelongate shaft assembly in an unarticulated orientation, according toone aspect of this disclosure.

FIG. 20 is another top view of the end effector of FIG. 16 showing theelongate shaft assembly in a first articulated orientation, according toone aspect of this disclosure.

FIG. 21 is another top view of the end effector of FIG. 16 showing theelongate shaft assembly in a second articulated orientation, accordingto one aspect of this disclosure.

FIG. 22 is a graph of a displacement member rate (velocity) as afunction of end effector articulation angle, in accordance with one ormore aspects of the present disclosure.

FIG. 23 is a graph of a displacement member force as a function offiring stroke displacement of the displacement member, in accordancewith one or more aspects of the present disclosure.

FIG. 24 is a graph of a displacement member force as a function offiring stroke displacement of the displacement member, in accordancewith one or more aspects of the present disclosure.

FIG. 25 is a graph of a displacement member rate as a function of alinear displacement stroke displacement of the displacement member, inaccordance with one or more aspects of the present disclosure.

FIG. 26 is a logic flow diagram depicting a process of a control programor a logic configuration for controlling the rate of a displacementmember such as an I-beam member based on articulation angle of the endeffector, in accordance with one or more aspects of the presentdisclosure.

FIG. 27 is a logic flow diagram depicting a process of a control programor a logic configuration for controlling the rate of a displacementmember such as a I-beam member based on articulation angle of the endeffector, in accordance with one or more aspects of the presentdisclosure.

DETAILED DESCRIPTION

Applicant of the present application owns the following patentapplications filed Jun. 20, 2017 and which are each herein incorporatedby reference in their respective entireties:

-   U.S. application Ser. No. 15/627,998, titled CONTROL OF MOTOR    VELOCITY OF A SURGICAL STAPLING AND CUTTING INSTRUMENT BASED ON    ANGLE OF ARTICULATION, by inventors Frederick E. Shelton, IV et al.,    filed Jun. 20, 2017, now U.S. Pat. No. 10,390,841.-   U.S. application Ser. No. 15/628,019, titled SURGICAL INSTRUMENT    WITH VARIABLE DURATION TRIGGER ARRANGEMENT, by inventors    Frederick E. Shelton, IV et al., filed Jun. 20, 2017, now U.S. Pat.    No. 10,881,396.-   U.S. application Ser. No. 15/628,036, titled SYSTEMS AND METHODS FOR    CONTROLLING DISPLACEMENT MEMBER MOTION OF A SURGICAL STAPLING AND    CUTTING INSTRUMENT, by inventors Frederick E. Shelton, IV et al.,    filed Jun. 20, 2017, now U.S. Pat. No. 11,090,046.-   U.S. application Ser. No. 15/628,075, titled SYSTEMS AND METHODS FOR    CONTROLLING MOTOR VELOCITY OF A SURGICAL STAPLING AND CUTTING    INSTRUMENT, by inventors Frederick E. Shelton, IV et al., filed Jun.    20, 2017, now U.S. Pat. No. 10,624,633.-   U.S. application Ser. No. 15/628,154, titled SURGICAL INSTRUMENT    HAVING CONTROLLABLE ARTICULATION VELOCITY, by inventors Frederick E.    Shelton, IV et al., filed Jun. 20, 2017, now U.S. Patent Application    Publication No. 2018/0360456.-   U.S. application Ser. No. 15/628,158, titled SYSTEMS AND METHODS FOR    CONTROLLING VELOCITY OF A DISPLACEMENT MEMBER OF A SURGICAL STAPLING    AND CUTTING INSTRUMENT, by inventors Frederick E. Shelton, IV et    al., filed Jun. 20, 2017, now U.S. Pat. No. 10,888,321.-   U.S. application Ser. No. 15/628,162, titled SYSTEMS AND METHODS FOR    CONTROLLING DISPLACEMENT MEMBER VELOCITY FOR A SURGICAL INSTRUMENT,    by inventors Frederick E. Shelton, IV et al., filed Jun. 20, 2017,    now U.S. Pat. No. 10,646,220.-   U.S. application Ser. No. 15/628,168, titled CONTROL OF MOTOR    VELOCITY OF A SURGICAL STAPLING AND CUTTING INSTRUMENT BASED ON    ANGLE OF ARTICULATION, by inventors Frederick E. Shelton, IV et al.,    filed Jun. 20, 2017, now U.S. Pat. No. 10,327,767.-   U.S. application Ser. No. 15/628,175, titled TECHNIQUES FOR ADAPTIVE    CONTROL OF MOTOR VELOCITY OF A SURGICAL STAPLING AND CUTTING    INSTRUMENT, by inventors Frederick E. Shelton, IV et al., filed Jun.    20, 2017, now U.S. Pat. No. 10,881,399.-   U.S. application Ser. No. 15/628,045, titled TECHNIQUES FOR CLOSED    LOOP CONTROL OF MOTOR VELOCITY OF A SURGICAL STAPLING AND CUTTING    INSTRUMENT, by inventors Raymond E. Parfett et al., filed Jun. 20,    2017, now U.S. Pat. No. 10,307,170.-   U.S. application Ser. No. 15/628,053, titled CLOSED LOOP FEEDBACK    CONTROL OF MOTOR VELOCITY OF A SURGICAL STAPLING AND CUTTING    INSTRUMENT BASED ON MAGNITUDE OF VELOCITY ERROR MEASUREMENTS, by    inventors Raymond E. Parfett et al., filed Jun. 20, 2017, now U.S.    Pat. No. 11,071,554.-   U.S. application Ser. No. 15/628,060, titled CLOSED LOOP FEEDBACK    CONTROL OF MOTOR VELOCITY OF A SURGICAL STAPLING AND CUTTING    INSTRUMENT BASED ON MEASURED TIME OVER A SPECIFIED DISPLACEMENT    DISTANCE, by inventors Jason L. Harris et al., filed Jun. 20, 2017,    now U.S. Pat. No. 11,382,638.-   U.S. application Ser. No. 15/628,067, titled CLOSED LOOP FEEDBACK    CONTROL OF MOTOR VELOCITY OF A SURGICAL STAPLING AND CUTTING    INSTRUMENT BASED ON MEASURED DISPLACEMENT DISTANCE TRAVELED OVER A    SPECIFIED TIME INTERVAL, by inventors Frederick E. Shelton, IV et    al., filed Jun. 20, 2017, now U.S. patent Ser. No. 11/517,325.-   U.S. application Ser. No. 15/628,072, titled CLOSED LOOP FEEDBACK    CONTROL OF MOTOR VELOCITY OF A SURGICAL STAPLING AND CUTTING    INSTRUMENT BASED ON MEASURED TIME OVER A SPECIFIED NUMBER OF SHAFT    ROTATIONS, by inventors Frederick E. Shelton, IV et al., filed Jun.    20, 2017, now U.S. Pat. No. 10,980,537.-   U.S. application Ser. No. 15/628,029, titled SYSTEMS AND METHODS FOR    CONTROLLING DISPLAYING MOTOR VELOCITY FOR A SURGICAL INSTRUMENT, by    inventors Jason L. Harris et al., filed Jun. 20, 2017, now U.S. Pat.    No. 10,368,864.-   U.S. application Ser. No. 15/628,077, titled SYSTEMS AND METHODS FOR    CONTROLLING MOTOR SPEED ACCORDING TO USER INPUT FOR A SURGICAL    INSTRUMENT, by inventors Jason L. Harris et al., filed Jun. 20,    2017, now U.S. Pat. No. 10,779,820.-   U.S. application Ser. No. 15/628,115, titled CLOSED LOOP FEEDBACK    CONTROL OF MOTOR VELOCITY OF A SURGICAL STAPLING AND CUTTING    INSTRUMENT BASED ON SYSTEM CONDITIONS, by inventors Frederick E.    Shelton, IV et al., filed Jun. 20, 2017, now U.S. Pat. No.    10,813,639.-   Applicant of the present application owns the following U.S. Design    patent applications filed Jun. 20, 2017 and which are each herein    incorporated by reference in their respective entireties:-   U.S. Design patent application Ser. No. 29/608,238, titled DISPLAY    PANEL WITH CHANGEABLE GRAPHICAL USER INTERFACE, by inventors    Jason L. Harris et al., filed Jun. 20, 2017, now U.S. Design Pat.    No. D879,809.-   U.S. Design patent application Ser. No. 29/608,231, titled DISPLAY    PANEL WITH GRAPHICAL USER INTERFACE, by inventors Jason L. Harris et    al., filed Jun. 20, 2017, now U.S. Design Pat. No. D879,808.-   U.S. Design patent application Ser. No. 29/608,246, titled DISPLAY    PANEL WITH CHANGEABLE GRAPHICAL USER INTERFACE, by inventors    Frederick E. Shelton, IV et al., filed Jun. 20, 2017, now U.S.    Design Pat. No. D890,784.

Certain aspects are shown and described to provide an understanding ofthe structure, function, manufacture, and use of the disclosed devicesand methods. Features shown or described in one example may be combinedwith features of other examples and modifications and variations arewithin the scope of this disclosure.

The terms “proximal” and “distal” are relative to a clinicianmanipulating the handle of the surgical instrument where “proximal”refers to the portion closer to the clinician and “distal” refers to theportion located further from the clinician. For expediency, spatialterms “vertical,” “horizontal,” “up,” and “down” used with respect tothe drawings are not intended to be limiting and/or absolute, becausesurgical instruments can used in many orientations and positions.

Example devices and methods are provided for performing laparascopic andminimally invasive surgical procedures. Such devices and methods,however, can be used in other surgical procedures and applicationsincluding open surgical procedures, for example. The surgicalinstruments can be inserted into a through a natural orifice or throughan incision or puncture hole formed in tissue. The working portions orend effector portions of the instruments can be inserted directly intothe body or through an access device that has a working channel throughwhich the end effector and elongated shaft of the surgical instrumentcan be advanced.

FIGS. 1-4 depict a motor-driven surgical instrument 10 for cutting andfastening that may or may not be reused. In the illustrated examples,the surgical instrument 10 includes a housing 12 that comprises a handleassembly 14 that is configured to be grasped, manipulated, and actuatedby the clinician. The housing 12 is configured for operable attachmentto an interchangeable shaft assembly 200 that has an end effector 300operably coupled thereto that is configured to perform one or moresurgical tasks or procedures. In accordance with the present disclosure,various forms of interchangeable shaft assemblies may be effectivelyemployed in connection with robotically controlled surgical systems. Theterm “housing” may encompass a housing or similar portion of a roboticsystem that houses or otherwise operably supports at least one drivesystem configured to generate and apply at least one control motion thatcould be used to actuate interchangeable shaft assemblies. The term“frame” may refer to a portion of a handheld surgical instrument. Theterm “frame” also may represent a portion of a robotically controlledsurgical instrument and/or a portion of the robotic system that may beused to operably control a surgical instrument. Interchangeable shaftassemblies may be employed with various robotic systems, instruments,components, and methods disclosed in U.S. Pat. No. 9,072,535, entitledSURGICAL STAPLING INSTRUMENTS WITH ROTATABLE STAPLE DEPLOYMENTARRANGEMENTS, which is herein incorporated by reference in its entirety.

FIG. 1 is a perspective view of a surgical instrument 10 that has aninterchangeable shaft assembly 200 operably coupled thereto according toone aspect of this disclosure. The housing 12 includes an end effector300 that comprises a surgical cutting and fastening device configured tooperably support a surgical staple cartridge 304 therein. The housing 12may be configured for use in connection with interchangeable shaftassemblies that include end effectors that are adapted to supportdifferent sizes and types of staple cartridges, have different shaftlengths, sizes, and types. The housing 12 may be employed with a varietyof interchangeable shaft assemblies, including assemblies configured toapply other motions and forms of energy such as, radio frequency (RF)energy, ultrasonic energy, and/or motion to end effector arrangementsadapted for use in connection with various surgical applications andprocedures. The end effectors, shaft assemblies, handles, surgicalinstruments, and/or surgical instrument systems can utilize any suitablefastener, or fasteners, to fasten tissue. For instance, a fastenercartridge comprising a plurality of fasteners removably stored thereincan be removably inserted into and/or attached to the end effector of ashaft assembly.

The handle assembly 14 may comprise a pair of interconnectable handlehousing segments 16, 18 interconnected by screws, snap features,adhesive, etc. The handle housing segments 16, 18 cooperate to form apistol grip portion 19 that can be gripped and manipulated by theclinician. The handle assembly 14 operably supports a plurality of drivesystems configured to generate and apply control motions tocorresponding portions of the interchangeable shaft assembly that isoperably attached thereto. A display may be provided below a cover 45.

FIG. 2 is an exploded assembly view of a portion of the surgicalinstrument 10 of FIG. 1 according to one aspect of this disclosure. Thehandle assembly 14 may include a frame 20 that operably supports aplurality of drive systems. The frame 20 can operably support a “first”or closure drive system 30, which can apply closing and opening motionsto the interchangeable shaft assembly 200. The closure drive system 30may include an actuator such as a closure trigger 32 pivotally supportedby the frame 20. The closure trigger 32 is pivotally coupled to thehandle assembly 14 by a pivot pin 33 to enable the closure trigger 32 tobe manipulated by a clinician. When the clinician grips the pistol gripportion 19 of the handle assembly 14, the closure trigger 32 can pivotfrom a starting or “unactuated” position to an “actuated” position andmore particularly to a fully compressed or fully actuated position.

The handle assembly 14 and the frame 20 may operably support a firingdrive system 80 configured to apply firing motions to correspondingportions of the interchangeable shaft assembly attached thereto. Thefiring drive system 80 may employ an electric motor 82 located in thepistol grip portion 19 of the handle assembly 14. The electric motor 82may be a DC brushed motor having a maximum rotational speed ofapproximately 25,000 RPM, for example. In other arrangements, the motormay include a brushless motor, a cordless motor, a synchronous motor, astepper motor, or any other suitable electric motor. The electric motor82 may be powered by a power source 90 that may comprise a removablepower pack 92. The removable power pack 92 may comprise a proximalhousing portion 94 configured to attach to a distal housing portion 96.The proximal housing portion 94 and the distal housing portion 96 areconfigured to operably support a plurality of batteries 98 therein.Batteries 98 may each comprise, for example, a Lithium Ion (LI) or othersuitable battery. The distal housing portion 96 is configured forremovable operable attachment to a control circuit board 100, which isoperably coupled to the electric motor 82. Several batteries 98connected in series may power the surgical instrument 10. The powersource 90 may be replaceable and/or rechargeable. A display 43, which islocated below the cover 45, is electrically coupled to the controlcircuit board 100. The cover 45 may be removed to expose the display 43.

The electric motor 82 can include a rotatable shaft (not shown) thatoperably interfaces with a gear reducer assembly 84 mounted in meshingengagement with a with a set, or rack, of drive teeth 122 on alongitudinally movable drive member 120. The longitudinally movabledrive member 120 has a rack of drive teeth 122 formed thereon formeshing engagement with a corresponding drive gear 86 of the gearreducer assembly 84.

In use, a voltage polarity provided by the power source 90 can operatethe electric motor 82 in a clockwise direction wherein the voltagepolarity applied to the electric motor by the battery can be reversed inorder to operate the electric motor 82 in a counter-clockwise direction.When the electric motor 82 is rotated in one direction, thelongitudinally movable drive member 120 will be axially driven in thedistal direction “DD.” When the electric motor 82 is driven in theopposite rotary direction, the longitudinally movable drive member 120will be axially driven in a proximal direction “PD.” The handle assembly14 can include a switch that can be configured to reverse the polarityapplied to the electric motor 82 by the power source 90. The handleassembly 14 may include a sensor configured to detect the position ofthe longitudinally movable drive member 120 and/or the direction inwhich the longitudinally movable drive member 120 is being moved.

Actuation of the electric motor 82 can be controlled by a firing trigger130 that is pivotally supported on the handle assembly 14. The firingtrigger 130 may be pivoted between an unactuated position and anactuated position.

Turning back to FIG. 1 , the interchangeable shaft assembly 200 includesan end effector 300 comprising an elongated channel 302 configured tooperably support a surgical staple cartridge 304 therein. The endeffector 300 may include an anvil 306 that is pivotally supportedrelative to the elongated channel 302. The interchangeable shaftassembly 200 may include an articulation joint 270. Construction andoperation of the end effector 300 and the articulation joint 270 are setforth in U.S. Patent Application Publication No. 2014/0263541, entitledARTICULATABLE SURGICAL INSTRUMENT COMPRISING AN ARTICULATION LOCK, whichis herein incorporated by reference in its entirety. The interchangeableshaft assembly 200 may include a proximal housing or nozzle 201comprised of nozzle portions 202, 203. The interchangeable shaftassembly 200 may include a closure tube 260 extending along a shaft axisSA that can be utilized to close and/or open the anvil 306 of the endeffector 300.

Turning back to FIG. 1 , the closure tube 260 is translated distally(direction “DD”) to close the anvil 306, for example, in response to theactuation of the closure trigger 32 in the manner described in theaforementioned reference U.S. Patent Application Publication No.2014/0263541. The anvil 306 is opened by proximally translating theclosure tube 260. In the anvil-open position, the closure tube 260 ismoved to its proximal position.

FIG. 3 is another exploded assembly view of portions of theinterchangeable shaft assembly 200 according to one aspect of thisdisclosure. The interchangeable shaft assembly 200 may include a firingmember 220 supported for axial travel within the spine 210. The firingmember 220 includes an intermediate firing shaft 222 configured toattach to a distal cutting portion or knife bar 280. The firing member220 may be referred to as a “second shaft” or a “second shaft assembly”.The intermediate firing shaft 222 may include a longitudinal slot 223 ina distal end configured to receive a tab 284 on the proximal end 282 ofthe knife bar 280. The longitudinal slot 223 and the proximal end 282may be configured to permit relative movement there between and cancomprise a slip joint 286. The slip joint 286 can permit theintermediate firing shaft 222 of the firing member 220 to articulate theend effector 300 about the articulation joint 270 without moving, or atleast substantially moving, the knife bar 280. Once the end effector 300has been suitably oriented, the intermediate firing shaft 222 can beadvanced distally until a proximal sidewall of the longitudinal slot 223contacts the tab 284 to advance the knife bar 280 and fire the staplecartridge positioned within the channel 302. The spine 210 has anelongated opening or window 213 therein to facilitate assembly andinsertion of the intermediate firing shaft 222 into the spine 210. Oncethe intermediate firing shaft 222 has been inserted therein, a top framesegment 215 may be engaged with the shaft frame 212 to enclose theintermediate firing shaft 222 and knife bar 280 therein. Operation ofthe firing member 220 may be found in U.S. Patent ApplicationPublication No. 2014/0263541. A spine 210 can be configured to slidablysupport a firing member 220 and the closure tube 260 that extends aroundthe spine 210. The spine 210 may slidably support an articulation driver230.

The interchangeable shaft assembly 200 can include a clutch assembly 400configured to selectively and releasably couple the articulation driver230 to the firing member 220. The clutch assembly 400 includes a lockcollar, or lock sleeve 402, positioned around the firing member 220wherein the lock sleeve 402 can be rotated between an engaged positionin which the lock sleeve 402 couples the articulation driver 230 to thefiring member 220 and a disengaged position in which the articulationdriver 230 is not operably coupled to the firing member 220. When thelock sleeve 402 is in the engaged position, distal movement of thefiring member 220 can move the articulation driver 230 distally and,correspondingly, proximal movement of the firing member 220 can move thearticulation driver 230 proximally. When the lock sleeve 402 is in thedisengaged position, movement of the firing member 220 is nottransmitted to the articulation driver 230 and, as a result, the firingmember 220 can move independently of the articulation driver 230. Thenozzle 201 may be employed to operably engage and disengage thearticulation drive system with the firing drive system in the variousmanners described in U.S. Patent Application Publication No.2014/0263541.

The interchangeable shaft assembly 200 can comprise a slip ring assembly600 which can be configured to conduct electrical power to and/or fromthe end effector 300 and/or communicate signals to and/or from the endeffector 300, for example. The slip ring assembly 600 can comprise aproximal connector flange 604 and a distal connector flange 601positioned within a slot defined in the nozzle portions 202, 203. Theproximal connector flange 604 can comprise a first face and the distalconnector flange 601 can comprise a second face positioned adjacent toand movable relative to the first face. The distal connector flange 601can rotate relative to the proximal connector flange 604 about the shaftaxis SA-SA (FIG. 1 ). The proximal connector flange 604 can comprise aplurality of concentric, or at least substantially concentric,conductors 602 defined in the first face thereof. A connector 607 can bemounted on the proximal side of the distal connector flange 601 and mayhave a plurality of contacts wherein each contact corresponds to and isin electrical contact with one of the conductors 602. Such anarrangement permits relative rotation between the proximal connectorflange 604 and the distal connector flange 601 while maintainingelectrical contact there between. The proximal connector flange 604 caninclude an electrical connector 606 that can place the conductors 602 insignal communication with a shaft circuit board, for example. In atleast one instance, a wiring harness comprising a plurality ofconductors can extend between the electrical connector 606 and the shaftcircuit board. The electrical connector 606 may extend proximallythrough a connector opening defined in the chassis mounting flange. U.S.Patent Application Publication No. 2014/0263551, entitled STAPLECARTRIDGE TISSUE THICKNESS SENSOR SYSTEM, is incorporated herein byreference in its entirety. U.S. Patent Application Publication No.2014/0263552, entitled STAPLE CARTRIDGE TISSUE THICKNESS SENSOR SYSTEM,is incorporated by reference in its entirety. Further details regardingslip ring assembly 600 may be found in U.S. Patent ApplicationPublication No. 2014/0263541.

The interchangeable shaft assembly 200 can include a proximal portionfixably mounted to the handle assembly 14 and a distal portion that isrotatable about a longitudinal axis. The rotatable distal shaft portioncan be rotated relative to the proximal portion about the slip ringassembly 600. The distal connector flange 601 of the slip ring assembly600 can be positioned within the rotatable distal shaft portion.

FIG. 4 is an exploded view of one aspect of an end effector 300 of thesurgical instrument 10 of FIG. 1 according to one aspect of thisdisclosure. The end effector 300 may include the anvil 306 and thesurgical staple cartridge 304. The anvil 306 may be coupled to anelongated channel 302. Apertures 199 can be defined in the elongatedchannel 302 to receive pins 152 extending from the anvil 306 to allowthe anvil 306 to pivot from an open position to a closed positionrelative to the elongated channel 302 and surgical staple cartridge 304.A firing bar 172 is configured to longitudinally translate into the endeffector 300. The firing bar 172 may be constructed from one solidsection, or may include a laminate material comprising a stack of steelplates. The firing bar 172 comprises an I-beam 178 and a cutting edge182 at a distal end thereof. A distally projecting end of the firing bar172 can be attached to the I-beam 178 to assist in spacing the anvil 306from a surgical staple cartridge 304 positioned in the elongated channel302 when the anvil 306 is in a closed position. The I-beam 178 mayinclude a sharpened cutting edge 182 to sever tissue as the I-beam 178is advanced distally by the firing bar 172. In operation, the I-beam 178may, or fire, the surgical staple cartridge 304. The surgical staplecartridge 304 can include a molded cartridge body 194 that holds aplurality of staples 191 resting upon staple drivers 192 withinrespective upwardly open staple cavities 195. A wedge sled 190 is drivendistally by the I-beam 178, sliding upon a cartridge tray 196 of thesurgical staple cartridge 304. The wedge sled 190 upwardly cams thestaple drivers 192 to force out the staples 191 into deforming contactwith the anvil 306 while the cutting edge 182 of the I-beam 178 seversclamped tissue.

The I-beam 178 can include upper pins 180 that engage the anvil 306during firing. The I-beam 178 may include middle pins 184 and a bottomfoot 186 to engage portions of the cartridge body 194, cartridge tray196, and elongated channel 302. When a surgical staple cartridge 304 ispositioned within the elongated channel 302, a slot 193 defined in thecartridge body 194 can be aligned with a longitudinal slot 197 definedin the cartridge tray 196 and a slot 189 defined in the elongatedchannel 302. In use, the I-beam 178 can slide through the alignedlongitudinal slots 193, 197, and 189 wherein, as indicated in FIG. 4 ,the bottom foot 186 of the I-beam 178 can engage a groove running alongthe bottom surface of elongated channel 302 along the length of slot189, the middle pins 184 can engage the top surfaces of cartridge tray196 along the length of longitudinal slot 197, and the upper pins 180can engage the anvil 306. The I-beam 178 can space, or limit therelative movement between, the anvil 306 and the surgical staplecartridge 304 as the firing bar 172 is advanced distally to fire thestaples from the surgical staple cartridge 304 and/or incise the tissuecaptured between the anvil 306 and the surgical staple cartridge 304.The firing bar 172 and the I-beam 178 can be retracted proximallyallowing the anvil 306 to be opened to release the two stapled andsevered tissue portions.

FIGS. 5A-5B is a block diagram of a control circuit 700 of the surgicalinstrument 10 of FIG. 1 spanning two drawing sheets according to oneaspect of this disclosure. Referring primarily to FIGS. 5A-5B, a handleassembly 702 may include a motor 714 which can be controlled by a motordriver 715 and can be employed by the firing system of the surgicalinstrument 10. In various forms, the motor 714 may be a DC brusheddriving motor having a maximum rotational speed of approximately 25,000RPM. In other arrangements, the motor 714 may include a brushless motor,a cordless motor, a synchronous motor, a stepper motor, or any othersuitable electric motor. The motor driver 715 may comprise an H-Bridgedriver comprising field-effect transistors (FETs) 719, for example. Themotor 714 can be powered by the power assembly 706 releasably mounted tothe handle assembly 200 for supplying control power to the surgicalinstrument 10. The power assembly 706 may comprise a battery which mayinclude a number of battery cells connected in series that can be usedas the power source to power the surgical instrument 10. In certaincircumstances, the battery cells of the power assembly 706 may bereplaceable and/or rechargeable. In at least one example, the batterycells can be Lithium-Ion batteries which can be separably couplable tothe power assembly 706.

The shaft assembly 704 may include a shaft assembly controller 722 whichcan communicate with a safety controller and power management controller716 through an interface while the shaft assembly 704 and the powerassembly 706 are coupled to the handle assembly 702. For example, theinterface may comprise a first interface portion 725 which may includeone or more electric connectors for coupling engagement withcorresponding shaft assembly electric connectors and a second interfaceportion 727 which may include one or more electric connectors forcoupling engagement with corresponding power assembly electricconnectors to permit electrical communication between the shaft assemblycontroller 722 and the power management controller 716 while the shaftassembly 704 and the power assembly 706 are coupled to the handleassembly 702. One or more communication signals can be transmittedthrough the interface to communicate one or more of the powerrequirements of the attached interchangeable shaft assembly 704 to thepower management controller 716. In response, the power managementcontroller may modulate the power output of the battery of the powerassembly 706, as described below in greater detail, in accordance withthe power requirements of the attached shaft assembly 704. Theconnectors may comprise switches which can be activated after mechanicalcoupling engagement of the handle assembly 702 to the shaft assembly 704and/or to the power assembly 706 to allow electrical communicationbetween the shaft assembly controller 722 and the power managementcontroller 716.

The interface can facilitate transmission of the one or morecommunication signals between the power management controller 716 andthe shaft assembly controller 722 by routing such communication signalsthrough a main controller 717 residing in the handle assembly 702, forexample. In other circumstances, the interface can facilitate a directline of communication between the power management controller 716 andthe shaft assembly controller 722 through the handle assembly 702 whilethe shaft assembly 704 and the power assembly 706 are coupled to thehandle assembly 702.

The main controller 717 may be any single core or multicore processorsuch as those known under the trade name ARM Cortex by TexasInstruments. In one aspect, the main controller 717 may be anLM4F230H5QR ARM Cortex-M4F Processor Core, available from TexasInstruments, for example, comprising on-chip memory of 256 KBsingle-cycle flash memory, or other non-volatile memory, up to 40 MHz, aprefetch buffer to improve performance above 40 MHz, a 32 KBsingle-cycle serial random access memory (SRAM), internal read-onlymemory (ROM) loaded with StellarisWare® software, 2 KB electricallyerasable programmable read-only memory (EEPROM), one or more pulse widthmodulation (PWM) modules, one or more quadrature encoder inputs (QEI)analog, one or more 12-bit Analog-to-Digital Converters (ADC) with 12analog input channels, details of which are available for the productdatasheet.

The safety controller may be a safety controller platform comprising twocontroller-based families such as TMS570 and RM4x known under the tradename Hercules ARM Cortex R4, also by Texas Instruments. The safetycontroller may be configured specifically for IEC 61508 and ISO 26262safety critical applications, among others, to provide advancedintegrated safety features while delivering scalable performance,connectivity, and memory options.

The power assembly 706 may include a power management circuit which maycomprise the power management controller 716, a power modulator 738, anda current sense circuit 736. The power management circuit can beconfigured to modulate power output of the battery based on the powerrequirements of the shaft assembly 704 while the shaft assembly 704 andthe power assembly 706 are coupled to the handle assembly 702. The powermanagement controller 716 can be programmed to control the powermodulator 738 of the power output of the power assembly 706 and thecurrent sense circuit 736 can be employed to monitor power output of thepower assembly 706 to provide feedback to the power managementcontroller 716 about the power output of the battery so that the powermanagement controller 716 may adjust the power output of the powerassembly 706 to maintain a desired output. The power managementcontroller 716 and/or the shaft assembly controller 722 each maycomprise one or more processors and/or memory units which may store anumber of software modules.

The surgical instrument 10 (FIGS. 1-4 ) may comprise an output device742 which may include devices for providing a sensory feedback to auser. Such devices may comprise, for example, visual feedback devices(e.g., an LCD display screen, LED indicators), audio feedback devices(e.g., a speaker, a buzzer) or tactile feedback devices (e.g., hapticactuators). In certain circumstances, the output device 742 may comprisea display 743 which may be included in the handle assembly 702. Theshaft assembly controller 722 and/or the power management controller 716can provide feedback to a user of the surgical instrument 10 through theoutput device 742. The interface can be configured to connect the shaftassembly controller 722 and/or the power management controller 716 tothe output device 742. The output device 742 can instead be integratedwith the power assembly 706. In such circumstances, communicationbetween the output device 742 and the shaft assembly controller 722 maybe accomplished through the interface while the shaft assembly 704 iscoupled to the handle assembly 702.

The control circuit 700 comprises circuit segments configured to controloperations of the powered surgical instrument 10. A safety controllersegment (Segment 1) comprises a safety controller and the maincontroller 717 segment (Segment 2). The safety controller and/or themain controller 717 are configured to interact with one or moreadditional circuit segments such as an acceleration segment, a displaysegment, a shaft segment, an encoder segment, a motor segment, and apower segment. Each of the circuit segments may be coupled to the safetycontroller and/or the main controller 717. The main controller 717 isalso coupled to a flash memory. The main controller 717 also comprises aserial communication interface. The main controller 717 comprises aplurality of inputs coupled to, for example, one or more circuitsegments, a battery, and/or a plurality of switches. The segmentedcircuit may be implemented by any suitable circuit, such as, forexample, a printed circuit board assembly (PCBA) within the poweredsurgical instrument 10. It should be understood that the term processoras used herein includes any microprocessor, processors, controller,controllers, or other basic computing device that incorporates thefunctions of a computer's central processing unit (CPU) on an integratedcircuit or at most a few integrated circuits. The main controller 717 isa multipurpose, programmable device that accepts digital data as input,processes it according to instructions stored in its memory, andprovides results as output. It is an example of sequential digitallogic, as it has internal memory. The control circuit 700 can beconfigured to implement one or more of the processes described herein.

The acceleration segment (Segment 3) comprises an accelerometer. Theaccelerometer is configured to detect movement or acceleration of thepowered surgical instrument 10. Input from the accelerometer may be usedto transition to and from a sleep mode, identify an orientation of thepowered surgical instrument, and/or identify when the surgicalinstrument has been dropped. In some examples, the acceleration segmentis coupled to the safety controller and/or the main controller 717.

The display segment (Segment 4) comprises a display connector coupled tothe main controller 717. The display connector couples the maincontroller 717 to a display through one or more integrated circuitdrivers of the display. The integrated circuit drivers of the displaymay be integrated with the display and/or may be located separately fromthe display. The display may comprise any suitable display, such as, forexample, an organic light-emitting diode (OLED) display, aliquid-crystal display (LCD), and/or any other suitable display. In someexamples, the display segment is coupled to the safety controller.

The shaft segment (Segment 5) comprises controls for an interchangeableshaft assembly 200 (FIGS. 1 and 3 ) coupled to the surgical instrument10 (FIGS. 1-4 ) and/or one or more controls for an end effector 300coupled to the interchangeable shaft assembly 200. The shaft segmentcomprises a shaft connector configured to couple the main controller 717to a shaft PCBA. The shaft PCBA comprises a low-power microcontrollerwith a ferroelectric random access memory (FRAM), an articulationswitch, a shaft release Hall effect switch, and a shaft PCBA EEPROM. Theshaft PCBA EEPROM comprises one or more parameters, routines, and/orprograms specific to the interchangeable shaft assembly 200 and/or theshaft PCBA. The shaft PCBA may be coupled to the interchangeable shaftassembly 200 and/or integral with the surgical instrument 10. In someexamples, the shaft segment comprises a second shaft EEPROM. The secondshaft EEPROM comprises a plurality of algorithms, routines, parameters,and/or other data corresponding to one or more shaft assemblies 200and/or end effectors 300 that may be interfaced with the poweredsurgical instrument 10.

The position encoder segment (Segment 6) comprises one or more magneticangle rotary position encoders. The one or more magnetic angle rotaryposition encoders are configured to identify the rotational position ofthe motor 714, an interchangeable shaft assembly 200 (FIGS. 1 and 3 ),and/or an end effector 300 of the surgical instrument 10 (FIGS. 1-4 ).In some examples, the magnetic angle rotary position encoders may becoupled to the safety controller and/or the main controller 717.

The motor circuit segment (Segment 7) comprises a motor 714 configuredto control movements of the powered surgical instrument 10 (FIGS. 1-4 ).The motor 714 is coupled to the main microcontroller processor 717 by anH-bridge driver comprising one or more H-bridge field-effect transistors(FETs) and a motor controller. The H-bridge driver is also coupled tothe safety controller. A motor current sensor is coupled in series withthe motor to measure the current draw of the motor. The motor currentsensor is in signal communication with the main controller 717 and/orthe safety controller. In some examples, the motor 714 is coupled to amotor electromagnetic interference (EMI) filter.

The motor controller controls a first motor flag and a second motor flagto indicate the status and position of the motor 714 to the maincontroller 717. The main controller 717 provides a pulse-widthmodulation (PWM) high signal, a PWM low signal, a direction signal, asynchronize signal, and a motor reset signal to the motor controllerthrough a buffer. The power segment is configured to provide a segmentvoltage to each of the circuit segments.

The power segment (Segment 8) comprises a battery coupled to the safetycontroller, the main controller 717, and additional circuit segments.The battery is coupled to the segmented circuit by a battery connectorand a current sensor. The current sensor is configured to measure thetotal current draw of the segmented circuit. In some examples, one ormore voltage converters are configured to provide predetermined voltagevalues to one or more circuit segments. For example, in some examples,the segmented circuit may comprise 3.3V voltage converters and/or 5Vvoltage converters. A boost converter is configured to provide a boostvoltage up to a predetermined amount, such as, for example, up to 13V.The boost converter is configured to provide additional voltage and/orcurrent during power intensive operations and prevent brownout orlow-power conditions.

A plurality of switches are coupled to the safety controller and/or themain controller 717. The switches may be configured to controloperations of the surgical instrument 10 (FIGS. 1-4 ), of the segmentedcircuit, and/or indicate a status of the surgical instrument 10. Abail-out door switch and Hall effect switch for bailout are configuredto indicate the status of a bail-out door. A plurality of articulationswitches, such as, for example, a left side articulation left switch, aleft side articulation right switch, a left side articulation centerswitch, a right side articulation left switch, a right side articulationright switch, and a right side articulation center switch are configuredto control articulation of an interchangeable shaft assembly 200 (FIGS.1 and 3 ) and/or the end effector 300 (FIGS. 1 and 4 ). A left sidereverse switch and a right side reverse switch are coupled to the maincontroller 717. The left side switches comprising the left sidearticulation left switch, the left side articulation right switch, theleft side articulation center switch, and the left side reverse switchare coupled to the main controller 717 by a left flex connector. Theright side switches comprising the right side articulation left switch,the right side articulation right switch, the right side articulationcenter switch, and the right side reverse switch are coupled to the maincontroller 717 by a right flex connector. A firing switch, a clamprelease switch, and a shaft engaged switch are coupled to the maincontroller 717.

Any suitable mechanical, electromechanical, or solid state switches maybe employed to implement the plurality of switches, in any combination.For example, the switches may be limit switches operated by the motionof components associated with the surgical instrument 10 (FIGS. 1-4 ) orthe presence of an object. Such switches may be employed to controlvarious functions associated with the surgical instrument 10. A limitswitch is an electromechanical device that consists of an actuatormechanically linked to a set of contacts. When an object comes intocontact with the actuator, the device operates the contacts to make orbreak an electrical connection. Limit switches are used in a variety ofapplications and environments because of their ruggedness, ease ofinstallation, and reliability of operation. They can determine thepresence or absence, passing, positioning, and end of travel of anobject. In other implementations, the switches may be solid stateswitches that operate under the influence of a magnetic field such asHall-effect devices, magneto-resistive (MR) devices, giantmagneto-resistive (GMR) devices, magnetometers, among others. In otherimplementations, the switches may be solid state switches that operateunder the influence of light, such as optical sensors, infrared sensors,ultraviolet sensors, among others. Still, the switches may be solidstate devices such as transistors (e.g., FET, Junction-FET, metal-oxidesemiconductor-FET (MOSFET), bipolar, and the like). Other switches mayinclude wireless switches, ultrasonic switches, accelerometers, inertialsensors, among others.

FIG. 6 is another block diagram of the control circuit 700 of thesurgical instrument of FIG. 1 illustrating interfaces between the handleassembly 702 and the power assembly 706 and between the handle assembly702 and the interchangeable shaft assembly 704 according to one aspectof this disclosure. The handle assembly 702 may comprise a maincontroller 717, a shaft assembly connector 726 and a power assemblyconnector 730. The power assembly 706 may include a power assemblyconnector 732, a power management circuit 734 that may comprise thepower management controller 716, a power modulator 738, and a currentsense circuit 736. The shaft assembly connectors 730, 732 form aninterface 727. The power management circuit 734 can be configured tomodulate power output of the battery 707 based on the power requirementsof the interchangeable shaft assembly 704 while the interchangeableshaft assembly 704 and the power assembly 706 are coupled to the handleassembly 702. The power management controller 716 can be programmed tocontrol the power modulator 738 of the power output of the powerassembly 706 and the current sense circuit 736 can be employed tomonitor power output of the power assembly 706 to provide feedback tothe power management controller 716 about the power output of thebattery 707 so that the power management controller 716 may adjust thepower output of the power assembly 706 to maintain a desired output. Theshaft assembly 704 comprises a shaft processor 719 coupled to anon-volatile memory 721 and shaft assembly connector 728 to electricallycouple the shaft assembly 704 to the handle assembly 702. The shaftassembly connectors 726, 728 form interface 725. The main controller717, the shaft processor 719, and/or the power management controller 716can be configured to implement one or more of the processes describedherein.

The surgical instrument 10 (FIGS. 1-4 ) may comprise an output device742 to a sensory feedback to a user. Such devices may comprise visualfeedback devices (e.g., an LCD display screen, LED indicators), audiofeedback devices (e.g., a speaker, a buzzer), or tactile feedbackdevices (e.g., haptic actuators). In certain circumstances, the outputdevice 742 may comprise a display 743 that may be included in the handleassembly 702. The shaft assembly controller 722 and/or the powermanagement controller 716 can provide feedback to a user of the surgicalinstrument 10 through the output device 742. The interface 727 can beconfigured to connect the shaft assembly controller 722 and/or the powermanagement controller 716 to the output device 742. The output device742 can be integrated with the power assembly 706. Communication betweenthe output device 742 and the shaft assembly controller 722 may beaccomplished through the interface 725 while the interchangeable shaftassembly 704 is coupled to the handle assembly 702. Having described acontrol circuit 700 (FIGS. 5A-5B and 6 ) for controlling the operationof the surgical instrument 10 (FIGS. 1-4 ), the disclosure now turns tovarious configurations of the surgical instrument 10 (FIGS. 1-4 ) andcontrol circuit 700.

FIG. 7 illustrates a control circuit 800 configured to control aspectsof the surgical instrument 10 (FIGS. 1-4 ) according to one aspect ofthis disclosure. The control circuit 800 can be configured to implementvarious processes described herein. The control circuit 800 may comprisea controller comprising one or more processors 802 (e.g.,microprocessor, microcontroller) coupled to at least one memory circuit804. The memory circuit 804 stores machine executable instructions thatwhen executed by the processor 802, cause the processor 802 to executemachine instructions to implement various processes described herein.The processor 802 may be any one of a number of single or multi-coreprocessors known in the art. The memory circuit 804 may comprisevolatile and non-volatile storage media. The processor 802 may includean instruction processing unit 806 and an arithmetic unit 808. Theinstruction processing unit may be configured to receive instructionsfrom the memory circuit 804.

FIG. 8 illustrates a combinational logic circuit 810 configured tocontrol aspects of the surgical instrument 10 (FIGS. 1-4 ) according toone aspect of this disclosure. The combinational logic circuit 810 canbe configured to implement various processes described herein. Thecircuit 810 may comprise a finite state machine comprising acombinational logic circuit 812 configured to receive data associatedwith the surgical instrument 10 at an input 814, process the data by thecombinational logic 812, and provide an output 816.

FIG. 9 illustrates a sequential logic circuit 820 configured to controlaspects of the surgical instrument 10 (FIGS. 1-4 ) according to oneaspect of this disclosure. The sequential logic circuit 820 or thecombinational logic circuit 822 can be configured to implement variousprocesses described herein. The circuit 820 may comprise a finite statemachine. The sequential logic circuit 820 may comprise a combinationallogic circuit 822, at least one memory circuit 824, and a clock 829, forexample. The at least one memory circuit 820 can store a current stateof the finite state machine. In certain instances, the sequential logiccircuit 820 may be synchronous or asynchronous. The combinational logiccircuit 822 is configured to receive data associated with the surgicalinstrument 10 an input 826, process the data by the combinational logiccircuit 822, and provide an output 828. In other aspects, the circuitmay comprise a combination of the processor 802 and the finite statemachine to implement various processes herein. In other aspects, thefinite state machine may comprise a combination of the combinationallogic circuit 810 and the sequential logic circuit 820.

Aspects may be implemented as an article of manufacture. The article ofmanufacture may include a computer readable storage medium arranged tostore logic, instructions, and/or data for performing various operationsof one or more aspects. For example, the article of manufacture maycomprise a magnetic disk, optical disk, flash memory, or firmwarecontaining computer program instructions suitable for execution by ageneral purpose processor or application specific processor.

FIG. 10 is a diagram of an absolute positioning system 1100 of thesurgical instrument 10 (FIGS. 1-4 ) where the absolute positioningsystem 1100 comprises a controlled motor drive circuit arrangementcomprising a sensor arrangement 1102 according to one aspect of thisdisclosure. The sensor arrangement 1102 for an absolute positioningsystem 1100 provides a unique position signal corresponding to thelocation of a displacement member 1111. Turning briefly to FIGS. 2-4 ,in one aspect the displacement member 1111 represents the longitudinallymovable drive member 120 (FIG. 2 ) comprising a rack of drive teeth 122for meshing engagement with a corresponding drive gear 86 of the gearreducer assembly 84. In other aspects, the displacement member 1111represents the firing member 220 (FIG. 3 ), which could be adapted andconfigured to include a rack of drive teeth. In yet another aspect, thedisplacement member 1111 represents the firing bar 172 (FIG. 4 ) or theI-beam 178 (FIG. 4 ), each of which can be adapted and configured toinclude a rack of drive teeth. Accordingly, as used herein, the termdisplacement member is used generically to refer to any movable memberof the surgical instrument 10 such as the drive member 120, the firingmember 220, the firing bar 172, the I-beam 178, or any element that canbe displaced. In one aspect, the longitudinally movable drive member 120is coupled to the firing member 220, the firing bar 172, and the I-beam178. Accordingly, the absolute positioning system 1100 can, in effect,track the linear displacement of the I-beam 178 by tracking the lineardisplacement of the longitudinally movable drive member 120. In variousother aspects, the displacement member 1111 may be coupled to any sensorsuitable for measuring linear displacement. Thus, the longitudinallymovable drive member 120, the firing member 220, the firing bar 172, orthe I-beam 178, or combinations, may be coupled to any suitable lineardisplacement sensor. Linear displacement sensors may include contact ornon-contact displacement sensors. Linear displacement sensors maycomprise linear variable differential transformers (LVDT), differentialvariable reluctance transducers (DVRT), a slide potentiometer, amagnetic sensing system comprising a movable magnet and a series oflinearly arranged Hall effect sensors, a magnetic sensing systemcomprising a fixed magnet and a series of movable linearly arranged Halleffect sensors, an optical sensing system comprising a movable lightsource and a series of linearly arranged photo diodes or photodetectors, or an optical sensing system comprising a fixed light sourceand a series of movable linearly arranged photo diodes or photodetectors, or any combination thereof.

An electric motor 1120 can include a rotatable shaft 1116 that operablyinterfaces with a gear assembly 1114 that is mounted in meshingengagement with a set, or rack, of drive teeth on the displacementmember 1111. A sensor element 1126 may be operably coupled to a gearassembly 1114 such that a single revolution of the sensor element 1126corresponds to some linear longitudinal translation of the displacementmember 1111. An arrangement of gearing and sensors 1118 can be connectedto the linear actuator via a rack and pinion arrangement or a rotaryactuator via a spur gear or other connection. A power source 1129supplies power to the absolute positioning system 1100 and an outputindicator 1128 may display the output of the absolute positioning system1100. In FIG. 2 , the displacement member 1111 represents thelongitudinally movable drive member 120 comprising a rack of drive teeth122 formed thereon for meshing engagement with a corresponding drivegear 86 of the gear reducer assembly 84. The displacement member 1111represents the longitudinally movable firing member 220, firing bar 172,I-beam 178, or combinations thereof.

A single revolution of the sensor element 1126 associated with theposition sensor 1112 is equivalent to a longitudinal linear displacementd1 of the of the displacement member 1111, where d1 is the longitudinallinear distance that the displacement member 1111 moves from point “a”to point “b” after a single revolution of the sensor element 1126coupled to the displacement member 1111. The sensor arrangement 1102 maybe connected via a gear reduction that results in the position sensor1112 completing one or more revolutions for the full stroke of thedisplacement member 1111. The position sensor 1112 may complete multiplerevolutions for the full stroke of the displacement member 1111.

A series of switches 1122 a-1122 n, where n is an integer greater thanone, may be employed alone or in combination with gear reduction toprovide a unique position signal for more than one revolution of theposition sensor 1112. The state of the switches 1122 a-1122 n are fedback to a controller 1104 that applies logic to determine a uniqueposition signal corresponding to the longitudinal linear displacementd1+d2+ . . . dn of the displacement member 1111. The output 1124 of theposition sensor 1112 is provided to the controller 1104. The positionsensor 1112 of the sensor arrangement 1102 may comprise a magneticsensor, an analog rotary sensor like a potentiometer, an array of analogHall-effect elements, which output a unique combination of positionsignals or values.

The absolute positioning system 1100 provides an absolute position ofthe displacement member 1111 upon power up of the instrument withoutretracting or advancing the displacement member 1111 to a reset (zero orhome) position as may be required with conventional rotary encoders thatmerely count the number of steps forwards or backwards that the motor1120 has taken to infer the position of a device actuator, drive bar,knife, and the like.

The controller 1104 may be programmed to perform various functions suchas precise control over the speed and position of the knife andarticulation systems. In one aspect, the controller 1104 includes aprocessor 1108 and a memory 1106. The electric motor 1120 may be abrushed DC motor with a gearbox and mechanical links to an articulationor knife system. In one aspect, a motor driver 1110 may be an A3941available from Allegro Microsystems, Inc. Other motor drivers may bereadily substituted for use in the absolute positioning system 1100. Amore detailed description of the absolute positioning system 1100 isdescribed in U.S. patent application Ser. No. 15/130,590, entitledSYSTEMS AND METHODS FOR CONTROLLING A SURGICAL STAPLING AND CUTTINGINSTRUMENT, filed on Apr. 15, 2016, the entire disclosure of which isherein incorporated by reference.

The controller 1104 may be programmed to provide precise control overthe speed and position of the displacement member 1111 and articulationsystems. The controller 1104 may be configured to compute a response inthe software of the controller 1104. The computed response is comparedto a measured response of the actual system to obtain an “observed”response, which is used for actual feedback decisions. The observedresponse is a favorable, tuned, value that balances the smooth,continuous nature of the simulated response with the measured response,which can detect outside influences on the system.

The absolute positioning system 1100 may comprise and/or be programmedto implement a feedback controller, such as a PID, state feedback, andadaptive controller. A power source 1129 converts the signal from thefeedback controller into a physical input to the system, in this casevoltage. Other examples include pulse width modulation (PWM) of thevoltage, current, and force. Other sensor(s) 1118 may be provided tomeasure physical parameters of the physical system in addition toposition measured by the position sensor 1112. In a digital signalprocessing system, absolute positioning system 1100 is coupled to adigital data acquisition system where the output of the absolutepositioning system 1100 will have finite resolution and samplingfrequency. The absolute positioning system 1100 may comprise a compareand combine circuit to combine a computed response with a measuredresponse using algorithms such as weighted average and theoreticalcontrol loop that drives the computed response towards the measuredresponse. The computed response of the physical system takes intoaccount properties like mass, inertial, viscous friction, inductanceresistance, etc., to predict what the states and outputs of the physicalsystem will be by knowing the input. The controller 1104 may be acontrol circuit 700 (FIGS. 5A-5B).

The motor driver 1110 may be an A3941 available from AllegroMicrosystems, Inc. The A3941 driver 1110 is a full-bridge controller foruse with external N-channel power metal oxide semiconductor field effecttransistors (MOSFETs) specifically designed for inductive loads, such asbrush DC motors. The driver 1110 comprises a unique charge pumpregulator provides full (>10 V) gate drive for battery voltages down to7 V and allows the A3941 to operate with a reduced gate drive, down to5.5 V. A bootstrap capacitor may be employed to provide theabove-battery supply voltage required for N-channel MOSFETs. An internalcharge pump for the high-side drive allows DC (100% duty cycle)operation. The full bridge can be driven in fast or slow decay modesusing diode or synchronous rectification. In the slow decay mode,current recirculation can be through the high-side or the lowside FETs.The power FETs are protected from shoot-through by resistor adjustabledead time. Integrated diagnostics provide indication of undervoltage,overtemperature, and power bridge faults, and can be configured toprotect the power MOSFETs under most short circuit conditions. Othermotor drivers may be readily substituted for use in the absolutepositioning system 1100.

Having described a general architecture for implementing aspects of anabsolute positioning system 1100 for a sensor arrangement 1102, thedisclosure now turns to FIGS. 11 and 12 for a description of one aspectof a sensor arrangement 1102 for the absolute positioning system 1100.FIG. 11 is an exploded perspective view of the sensor arrangement 1102for the absolute positioning system 1100 showing a circuit 1205 and therelative alignment of the elements of the sensor arrangement 1102,according to one aspect. The sensor arrangement 1102 for an absolutepositioning system 1100 comprises a position sensor 1200, a magnet 1202sensor element, a magnet holder 1204 that turns once every full strokeof the displacement member 1111, and a gear assembly 1206 to provide agear reduction. With reference briefly to FIG. 2 , the displacementmember 1111 may represent the longitudinally movable drive member 120comprising a rack of drive teeth 122 for meshing engagement with acorresponding drive gear 86 of the gear reducer assembly 84. Returningto FIG. 11 , a structural element such as bracket 1216 is provided tosupport the gear assembly 1206, the magnet holder 1204, and the magnet1202. The position sensor 1200 comprises magnetic sensing elements suchas Hall elements and is placed in proximity to the magnet 1202. As themagnet 1202 rotates, the magnetic sensing elements of the positionsensor 1200 determine the absolute angular position of the magnet 1202over one revolution.

The sensor arrangement 1102 may comprises any number of magnetic sensingelements, such as, for example, magnetic sensors classified according towhether they measure the total magnetic field or the vector componentsof the magnetic field. The techniques used to produce both types ofmagnetic sensors encompass many aspects of physics and electronics. Thetechnologies used for magnetic field sensing include search coil,fluxgate, optically pumped, nuclear precession, SQUID, Hall-effect,anisotropic magnetoresistance, giant magnetoresistance, magnetic tunneljunctions, giant magnetoimpedance, magnetostrictive/piezoelectriccomposites, magnetodiode, magnetotransistor, fiber optic, magnetooptic,and microelectromechanical systems-based magnetic sensors, among others.

A gear assembly comprises a first gear 1208 and a second gear 1210 inmeshing engagement to provide a 3:1 gear ratio connection. A third gear1212 rotates about a shaft 1214. The third gear 1212 is in meshingengagement with the displacement member 1111 (or 120 as shown in FIG. 2) and rotates in a first direction as the displacement member 1111advances in a distal direction D and rotates in a second direction asthe displacement member 1111 retracts in a proximal direction P. Thesecond gear 1210 also rotates about the shaft 1214 and, therefore,rotation of the second gear 1210 about the shaft 1214 corresponds to thelongitudinal translation of the displacement member 1111. Thus, one fullstroke of the displacement member 1111 in either the distal or proximaldirections D, P corresponds to three rotations of the second gear 1210and a single rotation of the first gear 1208. Since the magnet holder1204 is coupled to the first gear 1208, the magnet holder 1204 makes onefull rotation with each full stroke of the displacement member 1111.

The position sensor 1200 is supported by a position sensor holder 1218defining an aperture 1220 suitable to contain the position sensor 1200in precise alignment with a magnet 1202 rotating below within the magnetholder 1204. The fixture is coupled to the bracket 1216 and to thecircuit 1205 and remains stationary while the magnet 1202 rotates withthe magnet holder 1204. A hub 1222 is provided to mate with the firstgear 1208 and the magnet holder 1204. The second gear 1210 and thirdgear 1212 coupled to shaft 1214 also are shown.

FIG. 12 is a diagram of a position sensor 1200 for an absolutepositioning system 1100 comprising a magnetic rotary absolutepositioning system according to one aspect of this disclosure. Theposition sensor 1200 may be implemented as an AS5055EQFT single-chipmagnetic rotary position sensor available from Austria Microsystems, AG.The position sensor 1200 is interfaced with the controller 1104 toprovide an absolute positioning system 1100. The position sensor 1200 isa low-voltage and low-power component and includes four Hall-effectelements 1228A, 1228B, 1228C, 1228D in an area 1230 of the positionsensor 1200 that is located above the magnet 1202 (FIGS. 15 and 16 ). Ahigh-resolution ADC 1232 and a smart power management controller 1238are also provided on the chip. A CORDIC processor 1236 (for CoordinateRotation Digital Computer), also known as the digit-by-digit method andVolder's algorithm, is provided to implement a simple and efficientalgorithm to calculate hyperbolic and trigonometric functions thatrequire only addition, subtraction, bitshift, and table lookupoperations. The angle position, alarm bits, and magnetic fieldinformation are transmitted over a standard serial communicationinterface such as an SPI interface 1234 to the controller 1104. Theposition sensor 1200 provides 12 or 14 bits of resolution. The positionsensor 1200 may be an AS5055 chip provided in a small QFN 16-pin4×4×0.85 mm package.

The Hall-effect elements 1228A, 1228B, 1228C, 1228D are located directlyabove the rotating magnet 1202 (FIG. 11 ). The Hall-effect is awell-known effect and for expediency will not be described in detailherein, however, generally, the Hall-effect produces a voltagedifference (the Hall voltage) across an electrical conductor transverseto an electric current in the conductor and a magnetic fieldperpendicular to the current. A Hall coefficient is defined as the ratioof the induced electric field to the product of the current density andthe applied magnetic field. It is a characteristic of the material fromwhich the conductor is made, since its value depends on the type,number, and properties of the charge carriers that constitute thecurrent. In the AS5055 position sensor 1200, the Hall-effect elements1228A, 1228B, 1228C, 1228D are capable producing a voltage signal thatis indicative of the absolute position of the magnet 1202 in terms ofthe angle over a single revolution of the magnet 1202. This value of theangle, which is unique position signal, is calculated by the CORDICprocessor 1236 is stored onboard the AS5055 position sensor 1200 in aregister or memory. The value of the angle that is indicative of theposition of the magnet 1202 over one revolution is provided to thecontroller 1104 in a variety of techniques, e.g., upon power up or uponrequest by the controller 1104.

The AS5055 position sensor 1200 requires only a few external componentsto operate when connected to the controller 1104. Six wires are neededfor a simple application using a single power supply: two wires forpower and four wires 1240 for the SPI interface 1234 with the controller1104. A seventh connection can be added in order to send an interrupt tothe controller 1104 to inform that a new valid angle can be read. Uponpower-up, the AS5055 position sensor 1200 performs a full power-upsequence including one angle measurement. The completion of this cycleis indicated as an INT output 1242, and the angle value is stored in aninternal register. Once this output is set, the AS5055 position sensor1200 suspends to sleep mode. The controller 1104 can respond to the INTrequest at the INT output 1242 by reading the angle value from theAS5055 position sensor 1200 over the SPI interface 1234. Once the anglevalue is read by the controller 1104, the INT output 1242 is clearedagain. Sending a “read angle” command by the SPI interface 1234 by thecontroller 1104 to the position sensor 1200 also automatically powers upthe chip and starts another angle measurement. As soon as the controller1104 has completed reading of the angle value, the INT output 1242 iscleared and a new result is stored in the angle register. The completionof the angle measurement is again indicated by setting the INT output1242 and a corresponding flag in the status register.

Due to the measurement principle of the AS5055 position sensor 1200,only a single angle measurement is performed in very short time (˜600μs) after each power-up sequence. As soon as the measurement of oneangle is completed, the AS5055 position sensor 1200 suspends topower-down state. An on-chip filtering of the angle value by digitalaveraging is not implemented, as this would require more than one anglemeasurement and, consequently, a longer power-up time that is notdesired in low-power applications. The angle jitter can be reduced byaveraging of several angle samples in the controller 1104. For example,an averaging of four samples reduces the jitter by 6 dB (50%).

FIG. 13 is a section view of an end effector 2502 of the surgicalinstrument 10 (FIGS. 1-4 ) showing an I-beam 2514 firing stroke relativeto tissue 2526 grasped within the end effector 2502 according to oneaspect of this disclosure. The end effector 2502 is configured tooperate with the surgical instrument 10 shown in FIGS. 1-4 . The endeffector 2502 comprises an anvil 2516 and an elongated channel 2503 witha staple cartridge 2518 positioned in the elongated channel 2503. Afiring bar 2520 is translatable distally and proximally along alongitudinal axis 2515 of the end effector 2502. When the end effector2502 is not articulated, the end effector 2502 is in line with the shaftof the instrument. An I-beam 2514 comprising a cutting edge 2509 isillustrated at a distal portion of the firing bar 2520. A wedge sled2513 is positioned in the staple cartridge 2518. As the I-beam 2514translates distally, the cutting edge 2509 contacts and may cut tissue2526 positioned between the anvil 2516 and the staple cartridge 2518.Also, the I-beam 2514 contacts the wedge sled 2513 and pushes itdistally, causing the wedge sled 2513 to contact staple drivers 2511.The staple drivers 2511 may be driven up into staples 2505, causing thestaples 2505 to advance through tissue and into pockets 2507 defined inthe anvil 2516, which shape the staples 2505.

An example I-beam 2514 firing stroke is illustrated by a chart 2529aligned with the end effector 2502. Example tissue 2526 is also shownaligned with the end effector 2502. The firing member stroke maycomprise a stroke begin position 2527 and a stroke end position 2528.During an I-beam 2514 firing stroke, the I-beam 2514 may be advanceddistally from the stroke begin position 2527 to the stroke end position2528. The I-beam 2514 is shown at one example location of a stroke beginposition 2527. The I-beam 2514 firing member stroke chart 2529illustrates five firing member stroke regions 2517, 2519, 2521, 2523,2525. In a first firing stroke region 2517, the I-beam 2514 may begin toadvance distally. In the first firing stroke region 2517, the I-beam2514 may contact the wedge sled 2513 and begin to move it distally.While in the first region, however, the cutting edge 2509 may notcontact tissue and the wedge sled 2513 may not contact a staple driver2511. After static friction is overcome, the force to drive the I-beam2514 in the first region 2517 may be substantially constant.

In the second firing member stroke region 2519, the cutting edge 2509may begin to contact and cut tissue 2526. Also, the wedge sled 2513 maybegin to contact staple drivers 2511 to drive staples 2505. Force todrive the I-beam 2514 may begin to ramp up. As shown, tissue encounteredinitially may be compressed and/or thinner because of the way that theanvil 2516 pivots relative to the staple cartridge 2518. In the thirdfiring member stroke region 2521, the cutting edge 2509 may continuouslycontact and cut tissue 2526 and the wedge sled 2513 may repeatedlycontact staple drivers 2511. Force to drive the I-beam 2514 may plateauin the third region 2521. By the fourth firing stroke region 2523, forceto drive the I-beam 2514 may begin to decline. For example, tissue inthe portion of the end effector 2502 corresponding to the fourth firingregion 2523 may be less compressed than tissue closer to the pivot pointof the anvil 2516, requiring less force to cut. Also, the cutting edge2509 and wedge sled 2513 may reach the end of the tissue 2526 while inthe fourth region 2523. When the I-beam 2514 reaches the fifth region2525, the tissue 2526 may be completely severed. The wedge sled 2513 maycontact one or more staple drivers 2511 at or near the end of thetissue. Force to advance the I-beam 2514 through the fifth region 2525may be reduced and, in some examples, may be similar to the force todrive the I-beam 2514 in the first region 2517. At the conclusion of thefiring member stroke, the I-beam 2514 may reach the stroke end position2528. The positioning of firing member stroke regions 2517, 2519, 2521,2523, 2525 in FIG. 18 is just one example. In some examples, differentregions may begin at different positions along the end effectorlongitudinal axis 2515, for example, based on the positioning of tissuebetween the anvil 2516 and the staple cartridge 2518.

As discussed above and with reference now to FIGS. 10-13 , the electricmotor 1122 positioned within the handle assembly of the surgicalinstrument 10 (FIGS. 1-4 ) can be utilized to advance and/or retract thefiring system of the shaft assembly, including the I-beam 2514, relativeto the end effector 2502 of the shaft assembly in order to staple and/orincise tissue captured within the end effector 2502. The I-beam 2514 maybe advanced or retracted at a desired speed, or within a range ofdesired speeds. The controller 1104 may be configured to control thespeed of the I-beam 2514. The controller 1104 may be configured topredict the speed of the I-beam 2514 based on various parameters of thepower supplied to the electric motor 1122, such as voltage and/orcurrent, for example, and/or other operating parameters of the electricmotor 1122 or external influences. The controller 1104 may be configuredto predict the current speed of the I-beam 2514 based on the previousvalues of the current and/or voltage supplied to the electric motor1122, and/or previous states of the system like velocity, acceleration,and/or position. The controller 1104 may be configured to sense thespeed of the I-beam 2514 utilizing the absolute positioning sensorsystem described herein. The controller can be configured to compare thepredicted speed of the I-beam 2514 and the sensed speed of the I-beam2514 to determine whether the power to the electric motor 1122 should beincreased in order to increase the speed of the I-beam 2514 and/ordecreased in order to decrease the speed of the I-beam 2514. U.S. Pat.No. 8,210,411, entitled MOTOR-DRIVEN SURGICAL CUTTING INSTRUMENT, whichis incorporated herein by reference in its entirety. U.S. Pat. No.7,845,537, entitled SURGICAL INSTRUMENT HAVING RECORDING CAPABILITIES,which is incorporated herein by reference in its entirety.

Force acting on the I-beam 2514 may be determined using varioustechniques. The I-beam 2514 force may be determined by measuring themotor 2504 current, where the motor 2504 current is based on the loadexperienced by the I-beam 2514 as it advances distally. The I-beam 2514force may be determined by positioning a strain gauge on the drivemember 120 (FIG. 2 ), the firing member 220 (FIG. 2 ), I-beam 2514(I-beam 178, FIG. 20 ), the firing bar 172 (FIG. 2 ), and/or on aproximal end of the cutting edge 2509. The I-beam 2514 force may bedetermined by monitoring the actual position of the I-beam 2514 movingat an expected velocity based on the current set velocity of the motor2504 after a predetermined elapsed period T.sub.1 and comparing theactual position of the I-beam 2514 relative to the expected position ofthe I-beam 2514 based on the current set velocity of the motor 2504 atthe end of the period T.sub.1. Thus, if the actual position of theI-beam 2514 is less than the expected position of the I-beam 2514, theforce on the I-beam 2514 is greater than a nominal force. Conversely, ifthe actual position of the I-beam 2514 is greater than the expectedposition of the I-beam 2514, the force on the I-beam 2514 is less thanthe nominal force. The difference between the actual and expectedpositions of the I-beam 2514 is proportional to the deviation of theforce on the I-beam 2514 from the nominal force. Such techniques aredescribed in attorney docket number U.S. patent application Ser. No.15/628,075, titled SYSTEMS AND METHODS FOR CONTROLLING MOTOR VELOCITY OFA SURGICAL STAPLING AND CUTTING INSTRUMENT, now U.S. Pat. No. 10,624,633which is incorporated herein by reference in its entirety.

FIG. 14 illustrates a block diagram of a surgical instrument 2500programmed to control distal translation of a displacement memberaccording to one aspect of this disclosure. In one aspect, the surgicalinstrument 2500 is programmed to control distal translation of adisplacement member 1111 such as the I-beam 2514. The surgicalinstrument 2500 comprises an end effector 2502 that may comprise ananvil 2516, an I-beam 2514 (including a sharp cutting edge 2509), and aremovable staple cartridge 2518. The end effector 2502, anvil 2516,I-beam 2514, and staple cartridge 2518 may be configured as describedherein, for example, with respect to FIGS. 1-13 .

The position, movement, displacement, and/or translation of a linerdisplacement member 1111, such as the I-beam 2514, can be measured bythe absolute positioning system 1100, sensor arrangement 1102, andposition sensor 1200 as shown in FIGS. 10-12 and represented as positionsensor 2534 in FIG. 14 . Because the I-beam 2514 is coupled to thelongitudinally movable drive member 120, the position of the I-beam 2514can be determined by measuring the position of the longitudinallymovable drive member 120 employing the position sensor 2534.Accordingly, in the following description, the position, displacement,and/or translation of the I-beam 2514 can be achieved by the positionsensor 2534 as described herein. A control circuit 2510, such as thecontrol circuit 700 described in FIGS. 5A and 5B, may be programmed tocontrol the translation of the displacement member 1111, such as theI-beam 2514, as described in connection with FIGS. 10-12 . The controlcircuit 2510, in some examples, may comprise one or moremicrocontrollers, microprocessors, or other suitable processors forexecuting instructions that cause the processor or processors to controlthe displacement member, e.g., the I-beam 2514, in the manner described.In one aspect, a timer/counter circuit 2531 provides an output signal,such as elapsed time or a digital count, to the control circuit 2510 tocorrelate the position of the I-beam 2514 as determined by the positionsensor 2534 with the output of the timer/counter circuit 2531 such thatthe control circuit 2510 can determine the position of the I-beam 2514at a specific time (t) relative to a starting position. Thetimer/counter circuit 2531 may be configured to measure elapsed time,count external events, or time external events.

The control circuit 2510 may generate a motor set point signal 2522. Themotor set point signal 2522 may be provided to a motor controller 2508.The motor controller 2508 may comprise one or more circuits configuredto provide a motor drive signal 2524 to the motor 2504 to drive themotor 2504 as described herein. In some examples, the motor 2504 may bea brushed DC electric motor, such as the motor 82, 714, 1120 shown inFIGS. 1, 5B, 10 . For example, the velocity of the motor 2504 may beproportional to the motor drive signal 2524. In some examples, the motor2504 may be a brushless direct current (DC) electric motor and the motordrive signal 2524 may comprise a pulse-width-modulated (PWM) signalprovided to one or more stator windings of the motor 2504. Also, in someexamples, the motor controller 2508 may be omitted and the controlcircuit 2510 may generate the motor drive signal 2524 directly.

The motor 2504 may receive power from an energy source 2512. The energysource 2512 may be or include a battery, a super capacitor, or any othersuitable energy source 2512. The motor 2504 may be mechanically coupledto the I-beam 2514 via a transmission 2506. The transmission 2506 mayinclude one or more gears or other linkage components to couple themotor 2504 to the I-beam 2514. A position sensor 2534 may sense aposition of the I-beam 2514. The position sensor 2534 may be or includeany type of sensor that is capable of generating position data thatindicates a position of the I-beam 2514. In some examples, the positionsensor 2534 may include an encoder configured to provide a series ofpulses to the control circuit 2510 as the I-beam 2514 translatesdistally and proximally. The control circuit 2510 may track the pulsesto determine the position of the I-beam 2514. Other suitable positionsensor may be used, including, for example, a proximity sensor. Othertypes of position sensors may provide other signals indicating motion ofthe I-beam 2514. Also, in some examples, the position sensor 2534 may beomitted. Where the motor 2504 is a stepper motor, the control circuit2510 may track the position of the I-beam 2514 by aggregating the numberand direction of steps that the motor 2504 has been instructed toexecute. The position sensor 2534 may be located in the end effector2502 or at any other portion of the instrument.

The control circuit 2510 may be in communication with one or moresensors 2538. The sensors 2538 may be positioned on the end effector2502 and adapted to operate with the surgical instrument 2500 to measurethe various derived parameters such as gap distance versus time, tissuecompression versus time, and anvil strain versus time. The sensors 2538may comprise a magnetic sensor, a magnetic field sensor, a strain gauge,a pressure sensor, a force sensor, an inductive sensor such as an eddycurrent sensor, a resistive sensor, a capacitive sensor, an opticalsensor, and/or any other suitable sensor for measuring one or moreparameters of the end effector 2502. The sensors 2538 may include one ormore sensors.

The one or more sensors 2538 may comprise a strain gauge, such as amicro-strain gauge, configured to measure the magnitude of the strain inthe anvil 2516 during a clamped condition. The strain gauge provides anelectrical signal whose amplitude varies with the magnitude of thestrain. The sensors 2538 may comprise a pressure sensor configured todetect a pressure generated by the presence of compressed tissue betweenthe anvil 2516 and the staple cartridge 2518. The sensors 2538 may beconfigured to detect impedance of a tissue section located between theanvil 2516 and the staple cartridge 2518 that is indicative of thethickness and/or fullness of tissue located therebetween.

The sensors 2538 may be is configured to measure forces exerted on theanvil 2516 by the closure drive system 30. For example, one or moresensors 2538 can be at an interaction point between the closure tube 260(FIG. 3 ) and the anvil 2516 to detect the closure forces applied by theclosure tube 260 to the anvil 2516. The forces exerted on the anvil 2516can be representative of the tissue compression experienced by thetissue section captured between the anvil 2516 and the staple cartridge2518. The one or more sensors 2538 can be positioned at variousinteraction points along the closure drive system 30 (FIG. 2 ) to detectthe closure forces applied to the anvil 2516 by the closure drive system30. The one or more sensors 2538 may be sampled in real time during aclamping operation by a processor as described in FIGS. 5A-5B. Thecontrol circuit 2510 receives real-time sample measurements to provideanalyze time based information and assess, in real time, closure forcesapplied to the anvil 2516.

A current sensor 2536 can be employed to measure the current drawn bythe motor 2504. The force required to advance the I-beam 2514corresponds to the current drawn by the motor 2504. The force isconverted to a digital signal and provided to the control circuit 2510.

Using the physical properties of the instruments disclosed herein inconnection with FIGS. 1-14 , and with reference to FIG. 14 , the controlcircuit 2510 can be configured to simulate the response of the actualsystem of the instrument in the software of the controller. Adisplacement member can be actuated to move an I-beam 2514 in the endeffector 2502 at or near a target velocity. The surgical instrument 2500can include a feedback controller, which can be one of any feedbackcontrollers, including, but not limited to a PID, a State Feedback, LQR,and/or an Adaptive controller, for example. The surgical instrument 2500can include a power source to convert the signal from the feedbackcontroller into a physical input such as case voltage, pulse widthmodulated (PWM) voltage, frequency modulated voltage, current, torque,and/or force, for example.

The actual drive system of the surgical instrument 2500 is configured todrive the displacement member, cutting member, or I-beam 2514, by abrushed DC motor with gearbox and mechanical links to an articulationand/or knife system. Another example is the electric motor 2504 thatoperates the displacement member and the articulation driver, forexample, of an interchangeable shaft assembly. An outside influence isan unmeasured, unpredictable influence of things like tissue,surrounding bodies and friction on the physical system. Such outsideinfluence can be referred to as drag which acts in opposition to theelectric motor 2504. The outside influence, such as drag, may cause theoperation of the physical system to deviate from a desired operation ofthe physical system.

Before explaining aspects of the surgical instrument 2500 in detail, itshould be noted that the example aspects are not limited in applicationor use to the details of construction and arrangement of partsillustrated in the accompanying drawings and description. The exampleaspects may be implemented or incorporated in other aspects, variationsand modifications, and may be practiced or carried out in various ways.Further, unless otherwise indicated, the terms and expressions employedherein have been chosen for the purpose of describing the exampleaspects for the convenience of the reader and are not for the purpose oflimitation thereof. Also, it will be appreciated that one or more of thefollowing-described aspects, expressions of aspects and/or examples, canbe combined with any one or more of the other following-describedaspects, expressions of aspects and/or examples.

Various example aspects are directed to a surgical instrument 2500comprising an end effector 2502 with motor-driven surgical stapling andcutting implements. For example, a motor 2504 may drive a displacementmember distally and proximally along a longitudinal axis of the endeffector 2502. The end effector 2502 may comprise a pivotable anvil 2516and, when configured for use, a staple cartridge 2518 positionedopposite the anvil 2516. A clinician may grasp tissue between the anvil2516 and the staple cartridge 2518, as described herein. When ready touse the instrument 2500, the clinician may provide a firing signal, forexample by depressing a trigger of the instrument 2500. In response tothe firing signal, the motor 2504 may drive the displacement memberdistally along the longitudinal axis of the end effector 2502 from aproximal stroke begin position to a stroke end position distal of thestroke begin position. As the displacement member translates distally,an I-beam 2514 with a cutting element positioned at a distal end, maycut the tissue between the staple cartridge 2518 and the anvil 2516.

In various examples, the surgical instrument 2500 may comprise a controlcircuit 2510 programmed to control the distal translation of thedisplacement member, such as the I-beam 2514, for example, based on oneor more tissue conditions. The control circuit 2510 may be programmed tosense tissue conditions, such as thickness, either directly orindirectly, as described herein. The control circuit 2510 may beprogrammed to select a firing control program based on tissueconditions. A firing control program may describe the distal motion ofthe displacement member. Different firing control programs may beselected to better treat different tissue conditions. For example, whenthicker tissue is present, the control circuit 2510 may be programmed totranslate the displacement member at a lower velocity and/or with lowerpower. When thinner tissue is present, the control circuit 2510 may beprogrammed to translate the displacement member at a higher velocityand/or with higher power.

In some examples, the control circuit 2510 may initially operate themotor 2504 in an open-loop configuration for a first open-loop portionof a stroke of the displacement member. Based on a response of theinstrument 2500 during the open-loop portion of the stroke, the controlcircuit 2510 may select a firing control program. The response of theinstrument may include, a translation distance of the displacementmember during the open-loop portion, a time elapsed during the open-loopportion, energy provided to the motor 2504 during the open-loop portion,a sum of pulse widths of a motor drive signal, etc. After the open-loopportion, the control circuit 2510 may implement the selected firingcontrol program for a second portion of the displacement member stroke.For example, during the closed loop portion of the stroke, the controlcircuit 2510 may modulate the motor 2504 based on translation datadescribing a position of the displacement member in a closed-loop mannerto translate the displacement member at a constant velocity.

FIG. 15 illustrates a diagram 2580 plotting two example displacementmember strokes executed according to one aspect of this disclosure. Thediagram 2580 comprises two axes. A horizontal axis 2584 indicateselapsed time. A vertical axis 2582 indicates the position of the I-beam2514 between a stroke begin position 2586 and a stroke end position2588. On the horizontal axis 2584, the control circuit 2510 may receivethe firing signal and begin providing the initial motor setting att.sub.0. The open-loop portion of the displacement member stroke is aninitial time period that may elapse between t.sub.0 and t.sub.1.

A first example 2592 shows a response of the surgical instrument 2500when thick tissue is positioned between the anvil 2516 and the staplecartridge 2518. During the open-loop portion of the displacement memberstroke, e.g., the initial time period between t.sub.0 and t.sub.1, theI-beam 2514 may traverse from the stroke begin position 2586 to position2594. The control circuit 2510 may determine that position 2594corresponds to a firing control program that advances the I-beam 2514 ata selected constant velocity (Vslow), indicated by the slope of theexample 2592 after t.sub.1 (e.g., in the closed loop portion). Thecontrol circuit 2510 may drive I-beam 2514 to the velocity Vslow bymonitoring the position of I-beam 2514 and modulating the motor setpoint 2522 and/or motor drive signal 2524 to maintain Vslow. A secondexample 2590 shows a response of the surgical instrument 2500 when thintissue is positioned between the anvil 2516 and the staple cartridge2518.

During the initial time period (e.g., the open-loop period) betweent.sub.0 and t.sub.1, the I-beam 2514 may traverse from the stroke beginposition 2586 to position 2596. The control circuit may determine thatposition 2596 corresponds to a firing control program that advances thedisplacement member at a selected constant velocity (Vfast). Because thetissue in example 2590 is thinner than the tissue in example 2592, itmay provide less resistance to the motion of the I-beam 2514. As aresult, the I-beam 2514 may traverse a larger portion of the strokeduring the initial time period. Also, in some examples, thinner tissue(e.g., a larger portion of the displacement member stroke traversedduring the initial time period) may correspond to higher displacementmember velocities after the initial time period.

FIGS. 16-21 illustrate an end effector 2300 of a surgical instrument2010 showing how the end effector 2300 may be articulated relative tothe elongate shaft assembly 2200 about an articulation joint 2270according to one aspect of this disclosure. FIG. 16 is a partialperspective view of a portion of the end effector 2300 showing anelongate shaft assembly 2200 in an unarticulated orientation withportions thereof omitted for clarity. FIG. 17 is a perspective view ofthe end effector 2300 of FIG. 16 showing the elongate shaft assembly2200 in an unarticulated orientation. FIG. 18 is an exploded assemblyperspective view of the end effector 2300 of FIG. 16 showing theelongate shaft assembly 2200. FIG. 19 is a top view of the end effector2300 of FIG. 16 showing the elongate shaft assembly 2200 in anunarticulated orientation. FIG. 20 is a top view of the end effector2300 of FIG. 16 showing the elongate shaft assembly 2200 in a firstarticulated orientation. FIG. 21 is a top view of the end effector 2300of FIG. 16 showing the elongate shaft assembly 2200 in a secondarticulated orientation.

With reference now to FIGS. 16-21 , the end effector 2300 is adapted tocut and staple tissue and includes a first jaw in the form of anelongate channel 2302 that is configured to operably support a surgicalstaple cartridge 2304 therein. The end effector 2300 further includes asecond jaw in the form of an anvil 2310 that is supported on theelongate channel 2302 for movement relative thereto. The elongate shaftassembly 2200 includes an articulation system 2800 that employs anarticulation lock 2810. The articulation lock 2810 can be configured andoperated to selectively lock the surgical end effector 2300 in variousarticulated positions. Such arrangement enables the surgical endeffector 2300 to be rotated, or articulated, relative to the shaftclosure sleeve 260 when the articulation lock 2810 is in its unlockedstate. Referring specifically to FIG. 18 , the elongate shaft assembly2200 includes a spine 210 that is configured to (1) slidably support afiring member 220 therein and, (2) slidably support the closure sleeve260 (FIG. 16 ), which extends around the spine 210. The shaft closuresleeve 260 is attached to an end effector closure sleeve 272 that ispivotally attached to the closure sleeve 260 by a double pivot closuresleeve assembly 271.

The spine 210 also slidably supports a proximal articulation driver 230.The proximal articulation driver 230 has a distal end 231 that isconfigured to operably engage the articulation lock 2810. Thearticulation lock 2810 further comprises a shaft frame 2812 that isattached to the spine 210 in the various manners disclosed herein. Theshaft frame 2812 is configured to movably support a proximal portion2821 of a distal articulation driver 2820 therein. The distalarticulation driver 2820 is movably supported within the elongate shaftassembly 2200 for selective longitudinal travel in a distal direction DDand a proximal direction PD along an articulation actuation axis AAAthat is laterally offset and parallel to the shaft axis SA-SA inresponse to articulation control motions applied thereto.

In FIGS. 17 and 18 , the shaft frame 2812 includes a distal end portion2814 that has a pivot pin 2818 formed thereon. The pivot pin 2818 isadapted to be pivotally received within a pivot hole 2397 formed inpivot base portion 2395 of an end effector mounting assembly 2390. Theend effector mounting assembly 2390 is attached to the proximal end 2303of the elongate channel 2302 by a spring pin 2393 or equivalent. Thepivot pin 2818 defines an articulation axis B-B transverse to the shaftaxis SA-SA to facilitate pivotal travel (i.e., articulation) of the endeffector 2300 about the articulation axis B-B relative to the shaftframe 2812.

As shown in FIG. 18 , a link pin 2825 is formed on a distal end 2823 ofthe distal articulation link 2820 and is configured to be receivedwithin a hole 2904 in a proximal end 2902 of a cross link 2900. Thecross link 2900 extends transversely across the shaft axis SA-SA andincludes a distal end portion 2906. A distal link hole 2908 is providedthrough the distal end portion 2906 of the cross link 2900 and isconfigured to pivotally receive therein a base pin 2398 extending fromthe bottom of the pivot base portion 2395 of the end effector mountingassembly 2390. The base pin 2395 defines a link axis LA that is parallelto the articulation axis B-B. FIGS. 17 and 20 illustrate the surgicalend effector 2300 in an unarticulated position. The end effector axis EAis defined by the elongate channel 2302 is aligned with the shaft axisSA-SA. The term “aligned with” may mean “coaxially aligned” with theshaft axis SA-SA or parallel with the shaft axis SA-SA. Movement of thedistal articulation driver 2820 in the proximal direction PD will causethe cross link 2900 to draw the surgical end effector 2300 in aclockwise CW direction about the articulation axis B-B as shown in FIG.19 . Movement of the distal articulation driver 2820 in the distaldirection DD will cause the cross link 2900 to move the surgical endeffector 2300 in the counterclockwise CCW direction about thearticulation axis B-B as shown in FIG. 21 . As shown in FIG. 21 , thecross link 2900 has a curved shape that permits the cross-link 2900 tocurve around the articulation pin 2818 when the surgical end effector2300 is articulated in that direction. When the surgical end effector2300 is in a fully articulated position on either side of the shaft axisSA-SA, the articulation angle 2700 between the end effector axis EA andthe shaft axis SA-SA is approximately sixty-five degrees (65°). Thus,the range of articulation on either said of the shaft axis is from onedegree (1°) to sixty-five degrees (65°).

FIG. 19 shows the articulation joint 2270 in a straight position, i.e.,at a zero angle θ.sub.0 relative to the longitudinal direction depictedas shaft axis SA, according to one aspect. FIG. 20 shows thearticulation joint 2270 of FIG. 19 articulated in one direction at afirst angle θ.sub.1 defined between the shaft axis SA and the endeffector axis EA, according to one aspect. FIG. 21 illustrates thearticulation joint 2270 of FIG. 19 articulated in another direction at asecond angle θ.sub.2 defined between the shaft axis SA and the endeffector axis EA.

The surgical end effector 2300 in FIGS. 16-21 comprises a surgicalcutting and stapling device that employs a firing member 220 of thevarious types and configurations described herein. However, the surgicalend effector 2300 may comprise other forms of surgical end effectorsthat do not cut and/or staple tissue. A middle support member 2950 ispivotally and slidably supported relative to the spine 210. In FIG. 18 ,the middle support member 2950 includes a slot 2952 that is adapted toreceive therein a pin 2954 that protrudes from the spine 210. Thisenables the middle support member 2950 to pivot and translate relativeto the pin 2954 when the surgical end effector 2300 is articulated. Apivot pin 2958 protrudes from the underside of the middle support member2950 to be pivotally received within a corresponding pivot hole 2399provided in the base portion 2395 of the end effector mounting assembly2390. The middle support member 2950 further includes a slot 2960 forreceiving a firing member 220 there through. The middle support member2950 serves to provide lateral support to the firing member 220 as itflexes to accommodate articulation of the surgical end effector 2300.

The surgical instrument can additionally be configured to determine theangle at which the end effector 2300 is oriented. In various aspects,the position sensor 1112 of the sensor arrangement 1102 may comprise oneor more magnetic sensors, analog rotary sensors (such aspotentiometers), arrays of analog Hall effect sensors, which output aunique combination of position signals or values, among others, forexample. In one aspect, the articulation joint 2270 of the aspectillustrated in FIGS. 16-21 can additionally comprise an articulationsensor arrangement that is configured to determine the angular position,i.e., articulation angle, of the end effector 2300 and provide a uniqueposition signal corresponding thereto.

The articulation sensor arrangement can be similar to the sensorarrangement 1102 described above and illustrated in FIGS. 10-12 . Inthis aspect, the articulation sensor arrangement can comprise a positionsensor and a magnet that is operatively coupled to the articulationjoint 2270 such that it rotates in a manner consistent with the rotationof the articulation joint 2270. The magnet can, for example, be coupledto the pivot pin 2818. The position sensor comprises one or moremagnetic sensing elements, such as Hall effect sensors, and is placed inproximity to the magnet, either within or adjacent to the articulationjoint 2270. Accordingly, as the magnet rotates, the magnetic sensingelements of the position sensor determine the magnet's absolute angularposition. As the magnet is coupled to the articulation joint 2270, theangular position of the magnet with respect to the position sensorcorresponds to the angular position of the end effector 2300. Therefore,the articulation sensor arrangement is able to determine the angularposition of the end effector as the end effector articulates.

In another aspect, the surgical instrument is configured to determinethe angle at which the end effector 2300 is positioned in an indirectmanner by monitoring the absolute position of the articulation driver230 (FIG. 3 ). As the position of the articulation driver 230corresponds to the angle at which the end effector 2300 is oriented in aknown manner, the absolute position of the articulation driver 230 canbe tracked and then translated to the angular position of the endeffector 2300. In this aspect, the surgical instrument comprises anarticulation sensor arrangement that is configured to determine theabsolute linear position of the articulation driver 230 and provide aunique position signal corresponding thereto. In some aspects, thearticulation sensor arrangement or the controller operably coupled tothe articulation sensor arrangement is configured additionally totranslate or calculate the angular position of the end effector 2300from the unique position signal.

The articulation sensor arrangement in this aspect can likewise besimilar to the sensor arrangement 1102 described above and illustratedin FIGS. 10-12 . In one aspect similar to the aspect illustrated in FIG.10 with respect to the displacement member 1111, the articulation sensorarrangement comprises a position sensor and a magnet that turns onceevery full stroke of the longitudinally-movable articulation driver 230.The position sensor comprises one or more magnetic sensing elements,such as Hall effect sensors, and is placed in proximity to the magnet.Accordingly, as the magnet rotates, the magnetic sensing elements of theposition sensor determine the absolute angular position of the magnetover one revolution.

In one aspect, a single revolution of a sensor element associated withthe position sensor is equivalent to a longitudinal linear displacementd1 of the of the longitudinally-movable articulation driver 230. Inother words, d1 is the longitudinal linear distance that thelongitudinally-movable articulation driver 230 moves from point “a” topoint “b” after a single revolution of a sensor element coupled to thelongitudinally-movable articulation driver 230. The articulation sensorarrangement may be connected via a gear reduction that results in theposition sensor completing only one revolution for the full stroke ofthe longitudinally-movable articulation driver 230. In other words, d1can be equal to the full stroke of the articulation driver 230. Theposition sensor is configured to then transmit a unique position signalcorresponding to the absolute position of the articulation driver 230 tothe controller 1104, such as in those aspects depicted in FIG. 10 Uponreceiving the unique position signal, the controller 1104 is thenconfigured execute a logic to determine the angular position of the endeffector corresponding to the linear position of the articulation driver230 by, for example, querying a lookup table that returns the value ofthe pre-calculated angular position of the end effector 2300,calculating via an algorithm the angular position of the end effector2300 utilizing the linear position of the articulation driver 230 as theinput, or performing any other such method as is known in the field.

In various aspects, any number of magnetic sensing elements may beemployed on the articulation sensor arrangement, such as, for example,magnetic sensors classified according to whether they measure the totalmagnetic field or the vector components of the magnetic field. Thenumber of magnetic sensing elements utilized corresponds to the desiredresolution to be sensed by the articulation sensor arrangement. In otherwords, the larger number of magnetic sensing elements used, the finerdegree of articulation that can be sensed by the articulation sensorarrangement. The techniques used to produce both types of magneticsensors encompass many aspects of physics and electronics. Thetechnologies used for magnetic field sensing include search coil,fluxgate, optically pumped, nuclear precession, SQUID, Hall-effect,anisotropic magnetoresistance, giant magnetoresistance, magnetic tunneljunctions, giant magnetoimpedance, magnetostrictive/piezoelectriccomposites, magnetodiode, magnetotransistor, fiber optic, magnetooptic,and microelectromechanical systems-based magnetic sensors, among others.

In one aspect, the position sensor of the various aspects of thearticulation sensor arrangement may be implemented in a manner similarto the positioning system illustrated in FIG. 12 for tracking theposition of the displacement member 1111. In one such aspect, thearticulation sensor arrangement may be implemented as an AS5055EQFTsingle-chip magnetic rotary position sensor available from AustriaMicrosystems, AG. The position sensor is interfaced with the controllerto provide an absolute positioning system for determining the absoluteangular position of the end effector 2300, either directly orindirectly. The position sensor is a low voltage and low power componentand includes four Hall-effect elements 1228A, 1228B, 1228C, 1228D in anarea 1230 of the position sensor 1200 that is located above the magnet1202 (FIG. 11 ). A high resolution ADC 1232 and a smart power managementcontroller 1238 are also provided on the chip. A CORDIC processor 1236(for Coordinate Rotation Digital Computer), also known as thedigit-by-digit method and Volder's algorithm, is provided to implement asimple and efficient algorithm to calculate hyperbolic and trigonometricfunctions that require only addition, subtraction, bitshift, and tablelookup operations. The angle position, alarm bits and magnetic fieldinformation are transmitted over a standard serial communicationinterface such as an SPI interface 1234 to the controller 1104. Theposition sensor 1200 provides 12 or 14 bits of resolution. The positionsensor 1200 may be an AS5055 chip provided in a small QFN 16-pin4×4×0.85 mm package.

With reference to FIGS. 1-4 and 10-21 , the position of the articulationjoint 2270 and the position of the I-beam 178 (FIG. 4 ) can bedetermined with the absolute position feedback signal/value from theabsolute positioning system 1100. In one aspect, the articulation anglecan be determined fairly accurately based on the drive member 120 of thesurgical instrument 10. As described above, the movement of thelongitudinally movable drive member 120 (FIG. 2 ) can be tracked by theabsolute positioning system 1100 wherein, when the articulation drive isoperably coupled to the firing member 220 (FIG. 3 ) by the clutchassembly 400 (FIG. 3 ), for example, the absolute positioning system1100 can, in effect, track the movement of the articulation system viathe drive member 120. As a result of tracking the movement of thearticulation system, the controller of the surgical instrument can trackthe articulation angle θ of the end effector 2300, such as the endeffector 2300, for example. In various circumstances, as a result, thearticulation angle θ can be determined as a function of longitudinaldisplacement DL of the drive member 120. Since the longitudinaldisplacement DL of the drive member 120 can be precisely determinedbased on the absolute position signal/value provided by the absolutepositioning system 1100, the articulation angle θ can be determined as afunction of longitudinal displacement DL.

In another aspect, the articulation angle θ can be determined bylocating sensors on the articulation joint 2270. The sensors can beconfigured to sense rotation of the articulation joint 2270 using theabsolute positioning system 1100 adapted to measure absolute rotation ofthe articulation joint 2270. For example, the sensor arrangement 1102comprises a position sensor 1200, a magnet 1202, and a magnet holder1204 adapted to sense rotation of the articulation joint 2270. Theposition sensor 1200 comprises one or more than one magnetic sensingelements such as Hall elements and is placed in proximity to the magnet1202. The position sensor 1200 described in FIG. 12 can be adapted tomeasure the rotation angle of the articulation joint 2270. Accordingly,as the magnet 1202 rotates, the magnetic sensing elements of theposition sensor 1200 determine the absolute angular position of themagnet 1202 located on the articulation joint 2270. This information isprovided to the microcontroller 1104 to calculate the articulation angleof the articulation joint 2270. Accordingly, the articulation angle ofthe end effector 2300 can be determined by the absolute positioningsystem 1100 adapted to measure absolute rotation of the articulationjoint 2270.

In one aspect, the firing rate or velocity of the I-beam 178 may bevaried as a function of end effector 2300 articulation angle to lowerthe force-to-fire on the firing drive system 80 and, in particular, theforce-to-fire of the I-beam 178, among other components of the firingdrive system 80 discussed herein. To adapt to the variable firing forceof the I-beam 178 as a function of end effector 2300 articulation angle,a variable motor control voltage can be applied to the motor 82 tocontrol the velocity of the motor 82. The velocity of the motor 82 maybe controlled by comparing the I-beam 178 firing force to differentmaximum thresholds based on articulation angle of the end effector 2300.The velocity of the electric motor 82 can be varied by adjusting thevoltage, current, pulse width modulation (PWM), or duty cycle (0-100%)applied to the motor 82, for example.

Having described techniques for measuring the articulation angle of thearticulation joint 2270 and driving the longitudinally movable drivemember 120, the firing member 220, the firing bar 172, or the I-beam 178employing the firing drive system 80 of the surgical instrument 10(FIGS. 1-4 ) the description now turns to FIGS. 13, 14, and 22-27 for adescription of various techniques for controlling the firing rate orvelocity of the I-beam 2514, or the firing bar 2520, based on thearticulation angle of the end effector 2502.

FIG. 22 is a graph 4500 of the I-beam 2514 firing rate (velocity) as afunction of the end effector 2502 articulation angle, in accordance withone or more aspects of the present disclosure. The horizontal axis 4502represents end effector 2502 articulation angle varying from −65° to+65° degrees, for example, and the vertical axis 4504 represents theI-beam 2514 firing rate from 0 to 1.0Y mm/sec, where Y is a scalingfactor. For example, when Y=20, the vertical axis 4504 is scaled from 0to 20 mm/sec. The curve 4506 shows that as the end effector 2502articulation angle varies from −65° to +65° the E-beam 2514 firing ratevaries nonlinearly and is symmetric about 0°. The maximum I-beam 2514firing rate of 1.0Y occurs at an end effector 2300 articulation angle of0°, in other words, when the end effector axis EA and the shaft axis SAare aligned. As the end effector 2502 is articulated from 0° to +65° orfrom or 0° to −65° the I-beam 2514 firing rate decrease nonlinearly from1.0Y to 0.5Y.

FIG. 23 is a graph 4510 of I-beam 2514 firing force as a function offiring stroke displacement of the I-beam 2514, in accordance with one ormore aspects of the present disclosure. The horizontal axis 4512represents firing stroke displacement of the I-beam 2514 from 0 mm (thebeginning of the firing stroke) to 1.0X mm (the end of the firingstroke), where X is a scaling factor associated with the nominal lengthof a stapler cartridge. Nominal lengths of stapler cartridges range from10-60 mm, for example. The vertical axis 4514 represents I-beam 2514firing force from 0-1.00Y N (Newton), where Y is a scaling factor. Inone aspect, the firing member 2520 force varies from 0-900 N (0-202.328lbs-force). The graph 4510 shows three curves 4516, 4518, 4520. Thefirst curve 4516 represents I-beam 2514 firing force as a function offiring stroke displacement of the I-beam 2514 at an end effector 2502articulation angle of 0° (the end effector axis EA and the shaft axis SAare aligned) as the I-beam 2514 advances distally at a constantvelocity. The second curve 4518 represents I-beam 2514 firing force as afunction of firing stroke displacement of the I-beam 2514 at an endeffector 2502 articulation angle of ±65° as the I-beam 2514 advancesdistally at a constant velocity. In other words, without varying thevelocity of the motor 2504 as a function of the articulation angle ofthe end effector 2502. As shown by the second curve 4520 relative to thefirst curve 4516, the I-beam 2514 force as a function of firing strokedisplacement of the I-beam 2514 is greater when the I-beam 2514 advancesdistally at a constant velocity at an end effector 2502 articulationangle of ±65°. The third curve 4520 shows an overall lower I-beam 2514firing force as a function of firing stroke displacement of the I-beam2514 that is achieved by varying the velocity of the motor 2504 as afunction of end effector 2502 articulation angle from ±65° as shown inFIG. 22 , for example.

Force acting on the firing member 2520 may be determined using varioustechniques. In one aspect, the firing member force may be determined bymeasuring the motor 2504 current, where the motor 2504 current is basedon the load experienced by the firing member 2520 as it advancesdistally. In another aspect, the I-beam 2514 firing force may bedetermined by positioning a strain gauge on the drive member 120 (FIG. 2), the firing member 220 (FIG. 2 ), the firing member 2520, the firingbar 172 (FIG. 2 ), and/or the I-beam 2514, 178 (FIG. 4 ). In yet anotheraspect, the I-beam 2514 firing force may be determined by monitoring theactual position of the I-beam 2514 moving at an expected velocity basedon the current set velocity of the motor 2504 after a predeterminedelapsed period T.sub.1 and comparing the actual position of the I-beam2514 relative to the expected position of the I-beam 2514 based on thecurrent set velocity of the motor 2504 at the end of the period T.sub.1.Thus, if the actual position of the I-beam 2514 is less than theexpected position of the I-beam 2514, the force on the I-beam 2514 isgreater than a nominal force. Conversely, if the actual position of theI-beam 2514 is greater than the expected position of the I-beam 2514,the force on the I-beam 2514 is less than the nominal force. Thedifference between the actual and expected positions of the I-beam 2514is proportional to the deviation of the force on the I-beam 2514 fromthe nominal force. The latter technique is described in detail incommonly owned attorney docket number U.S. patent application Ser. No.15/628,075, titled SYSTEMS AND METHODS FOR CONTROLLING MOTOR VELOCITY OFA SURGICAL STAPLING AND CUTTING INSTRUMENT, now U.S. Pat. No. 10,624,633filed on Jun. 20, 2017, which is incorporated herein by reference in itsentirety. As the firing force of the I-beam 2514 varies as a function ofend effector 2502 articulation angle, varying the control voltageapplied to the motor 2504 to control the velocity of the motor 2504through differing maximum current thresholds related to end effector2502 articulation angle can be employed to reduce the firing force onthe I-beam 2514 and force-to-fire the I-beam 2514 generally. This istechnique is described below in connection with FIG. 23 .

FIG. 24 is a graph 4530 of I-beam 2514 firing force as a function offiring stroke displacement of the I-beam 2514, in accordance with one ormore aspects of the present disclosure. The horizontal axis 4532represents firing stroke displacement from 0-1.0X mm, where X is ascaling factor associated with the nominal length of a staplercartridge. Nominal lengths of stapler cartridges range from 10-60 mm,for example. The vertical axis 4534 represents I-beam 2514 firing forcefrom 0-1.00Y N, where Y is a scaling factor. In one aspect, the I-beam2514 firing force varies from 0-900 N (0-202.328 lbs-force). The graph4530 shows three curves 4536, 4538, 4540 and two thresholds 4542, 4544based on end effector 2502 articulation angle to reduce the firing forceand force-to-fire on the I-beam 2514. The first curve 4536 representsI-beam 2514 firing force as a function of firing stroke displacement atan end effector 2502 articulation angle of 0° (the end effector axis EAand the shaft axis SA are aligned) as the I-beam 2514 advances distallyat a constant velocity. The second curve 4538 represents I-beam 2514firing force as a function of firing stroke displacement of the I-beam2514 at an end effector 2502 articulation angle of 65° as the firingmember advances distally at a variable velocity set by articulationangle. The third curve 4540 represents I-beam 2514 firing force as afunction of firing stroke displacement of the I-beam 2514 at an endeffector 2502 articulation angle of 65° as the I-beam 2514 advances at aconstant desired velocity with actual battery capacity (V-A)limitations.

The graph 4530 also shows variable I-beam 2514 firing force triggerthresholds 4542, 4544 based on the articulation angle of the endeffector 2502, which results in a variable I-beam 2514 firing ratethroughout the I-beam 2514 firing stroke. The upper threshold 4542 isfor an end effector 2502 articulation angle of 65° and the lowerthreshold 4544 for an end effector 2502 articulation angle of 0°. Withthe end effector 2502 articulation angle set to 65° the I-beam 2514advances at a variable velocity until the I-beam 2514 firing forcecrosses the upper threshold 4542, at which time, an algorithm adjuststhe velocity of the motor 2504 to a desired velocity until the I-beam2514 firing force drops below the I-beam 2514 firing force upperthreshold 4542 and then holds the velocity of the motor 2054 constant.The I-beam 2514 then advances distally at the constant desired velocity.With the end effector 2502 articulation angle set to 0° the I-beam 2514advances at a variable velocity until the I-beam 2514 firing forcecrosses the lower threshold 4544, at which time, an algorithm adjuststhe velocity of the motor 2504 to a constant desired velocity. TheI-beam 2514 advances distally at the constant desired velocity. Thisoperation is further described below in connection with FIG. 24 . Theupper threshold 4542 and the lower threshold 4544 as well as interveningthreshold therebetween that vary based on the articulation angle of theend effector 2502, are nonlinear across the firing stroke displacementof the stapler cartridge 2518. In other aspects, the thresholds 4542,4544 may be a straight line constant or may be a straight line with aslope. The thresholds 4542, 4544 represent I-beam 2514 firing forceregardless how the I-beam 2514 firing force is determined.

As discussed above, the I-beam 2514 firing force may be determined bymotor 2504 current, strain gauge, or represented by comparing the actualposition of the I-beam 2514 over a predetermined period t.sub.1 relativeto the expected position of the I-beam 2514 advancing distally at a setmotor 2504 velocity. In the latter configuration, with reference also toFIG. 25 , the surgical instrument further comprises a timer/countercircuit 2531 coupled to the control circuit 2510, where thetimer/counter circuit 2531 is configured to measure elapsed time. Thecontrol circuit 2510 is configured to set the motor 2504 velocity,receive an initial position of the I-beam 2514 from the position sensor2534, receive a reference time t1 from the timer/counter circuit 2531corresponding to the initial position of the I-beam 2514, and determinean anticipated position of the I-beam 2514 at a time t.sub.2 based onthe set motor 2504 velocity. The control circuit 2510 is further isconfigured to receive an actual position of the I-beam 2514 at the timet.sub.2 from the position sensor 2534, compare the actual position ofthe I-beam 2514 at the time t.sub.2 with the anticipated position of theI-beam 2514 at the time t.sub.2, and determine the firing force on theI-beam 2514 based on a difference between the actual position of theI-beam 2514 at the time t.sub.2 with the anticipated position of theI-beam 2514 at the time t.sub.2.

FIG. 25 is a graph 4550 of I-beam 2514 firing rate as a function offiring stroke displacement of the I-beam 2514, in accordance with one ormore aspects of the present disclosure. The horizontal axis 4552represents I-beam 2514 firing stroke displacement from 0-1.0X mm, whereX is a scaling factor associated with the nominal length of a staplercartridge. Nominal lengths of stapler cartridges range from 10-60 mm,for example. The vertical axis 4554 represents I-beam 2514 firing ratefrom 0-1.00Y N, where Y is a scaling factor. In one aspect, the I-beam2514 force varies from 0-20 mm/sec. The graph 4550 shows three curves4556, 4558, 4559. The first curve 4556 is the I-beam 2514 rate set at anend effector articulation angle of 0°. The firing rate of the I-beam2514 increases over the initial displacement and remains constantthroughout the remaining stroke with the motor 2504 set to a constantvelocity. The second curve 4558 is the firing rate of the I-beam 2514set at an end effector 2502 articulation angle of 65°. The I-beam 2514firing rate increases over the initial displacement and remains constantthroughout the remaining stroke with the motor 2504 set to a variablevelocity based on the articulation angle of the end effector 2502. Thethird curve 4559 is the firing rate of the I-beam 2514 set at an endeffector 2502 articulation angle of 65°. The I-beam 2514 increases overthe initial displacement and varies throughout the remaining stroke withthe motor 2504 set to a constant desired velocity with actual batterycapacity (V-A) limitations.

FIG. 26 is a logic flow diagram depicting a process 4560 of a controlprogram or a logic configuration for controlling the rate of adisplacement member such as an I-beam 2514, for example, based onarticulation angle of the end effector 2502, in accordance with one ormore aspects of the present disclosure. In the following description ofthe process 4560 in FIG. 26 reference also should be made to FIG. 15-25. Accordingly, the control circuit 2510 determines 4562 the currentarticulation angle of the end effector 2502 based on informationreceived from the position sensor 2534. The control circuit 2510 sets4564 the velocity of the motor 2504 based on the articulation angle. Thecontrol circuit 2510 compares 4565 the current articulation angle to theprevious articulation angle. If there is no change in articulationangle, the process 4560 continues along no branch (N) and the controlcircuit 2510 determines 4562 the articulation angle while maintainingthe velocity of the motor 2504 constant. If there is a change inarticulation angle of the end effector 2502, the process 4560 continuesalong yes branch (Y) and the control circuit 2501 adjusts 4566 thevelocity of the motor 2504 based on the new articulation angle. Thecontrol circuit 2510 compares 4567 the actual position of the I-beam2514 to the end of the firing stroke position. If the I-beam 2514 is atthe end of the firing stroke, the process 4560 continues along the yesbranch (Y) and ends 4568. If the I-beam 2514 has not reached the end ofthe firing stroke, the process 4560 continues along the no branch (N)and determines 4562 the articulation angle. The process 4560 continuesuntil the position of the I-beam 2514 reaches 4569 the end of the firingstroke of the I-beam 2514.

FIG. 27 is a logic flow diagram depicting a process 4570 of a controlprogram or a logic configuration for controlling the rate of adisplacement member such as an I-beam 2514, for example, based onarticulation angle of the end effector 2502, in accordance with one ormore aspects of the present disclosure. In the following description ofthe process 4570 in FIG. 27 reference also should be made to FIG. 15-25. Accordingly, the control circuit 2510 determines 4572 the articulationangle of the end effector 2502 based on information received from theposition sensor 2534. In the example where the displacement member isthe I-beam 2514, the control circuit 2510 selects 4574 an I-beam 2514force threshold based on the articulation angle of the end effector2502. The control circuit 2510 provides a motor set point signal 2522 tothe motor controller 2508, which provides the motor drive signal 2524 toset 4576 the velocity of the motor 2504 based on the articulation angleof the end effector 2502. The control circuit 2510 determines 4578 theactual position of the I-beam 2514 and determines 4580 the I-beam 2514firing force and compares 4582 the I-beam 2514 firing force with thethreshold. If the I-beam 2514 firing force exceeds the threshold, theprocess continues along yes (Y) branch and the lowers 4584 the velocityof the motor 2504 until the I-beam 2514 firing force drops below theI-beam 2514 firing force threshold. If the I-beam 2514 firing force isless than the threshold, the process continues along no (N) branch andcontinues to determine 4578 the actual position of the I-beam 2514,determine 4580 the I-beam 2514 firing force, and compare 4582 the I-beam2514 firing force with the threshold until the I-beam 2514 firing forceexceeds the threshold. The motor drive signal 2524 may be a varyingvoltage or current signal, a pulse-width-modulated (PWM) signal, and/ora variable duty cycle signal. The control circuit 2510 compares theactual position of the I-beam 2514 to the end of I-beam 2514 firingstroke position. If the I-beam 2514 is at the end of the firing stroke,the process 4570 continues along the yes branch (Y) and ends 4588. Ifthe I-beam 2514 has not reached the end of the firing stroke, theprocess 4570 continues along the no branch (N) and determines 4572 thearticulation angle of the end effector 2502. The process 4570 continuesuntil the I-beam 2514 reaches the end of the firing stroke.

The functions or processes 4560, 4570 described herein may be executedby any of the processing circuits described herein, such as the controlcircuit 700 described in connection with FIGS. 5-6 , the circuits 800,810, 820 described in FIGS. 7-9 , the microcontroller 1104 described inwith FIGS. 10 and 12 , and/or the control circuit 2510 described in FIG.14 .

Aspects of the motorized surgical instrument may be practiced withoutthe specific details disclosed herein. Some aspects have been shown asblock diagrams rather than detail. Parts of this disclosure may bepresented in terms of instructions that operate on data stored in acomputer memory. An algorithm refers to a self-consistent sequence ofsteps leading to a desired result, where a “step” refers to amanipulation of physical quantities which may take the form ofelectrical or magnetic signals capable of being stored, transferred,combined, compared, and otherwise manipulated. These signals may bereferred to as bits, values, elements, symbols, characters, terms,numbers. These and similar terms may be associated with the appropriatephysical quantities and are merely convenient labels applied to thesequantities.

Generally, aspects described herein which can be implemented,individually and/or collectively, by a wide range of hardware, software,firmware, or any combination thereof can be viewed as being composed ofvarious types of “electrical circuitry.” Consequently, “electricalcircuitry” includes electrical circuitry having at least one discreteelectrical circuit, electrical circuitry having at least one integratedcircuit, electrical circuitry having at least one application specificintegrated circuit, electrical circuitry forming a general purposecomputing device configured by a computer program (e.g., a generalpurpose computer or processor configured by a computer program which atleast partially carries out processes and/or devices described herein,electrical circuitry forming a memory device (e.g., forms of randomaccess memory), and/or electrical circuitry forming a communicationsdevice (e.g., a modem, communications switch, or optical-electricalequipment). These aspects may be implemented in analog or digital form,or combinations thereof.

The foregoing description has set forth aspects of devices and/orprocesses via the use of block diagrams, flowcharts, and/or examples,which may contain one or more functions and/or operation. Each functionand/or operation within such block diagrams, flowcharts, or examples canbe implemented, individually and/or collectively, by a wide range ofhardware, software, firmware, or virtually any combination thereof. Inone aspect, several portions of the subject matter described herein maybe implemented via Application Specific Integrated Circuits (ASICs),Field Programmable Gate Arrays (FPGAs), digital signal processors(DSPs), Programmable Logic Devices (PLDs), circuits, registers and/orsoftware components, e.g., programs, subroutines, logic and/orcombinations of hardware and software components, logic gates, or otherintegrated formats. Some aspects disclosed herein, in whole or in part,can be equivalently implemented in integrated circuits, as one or morecomputer programs running on one or more computers (e.g., as one or moreprograms running on one or more computer systems), as one or moreprograms running on one or more processors (e.g., as one or moreprograms running on one or more microprocessors), as firmware, or asvirtually any combination thereof, and that designing the circuitryand/or writing the code for the software and or firmware would be wellwithin the skill of one of skill in the art in light of this disclosure.

The mechanisms of the disclosed subject matter are capable of beingdistributed as a program product in a variety of forms, and that anillustrative aspect of the subject matter described herein appliesregardless of the particular type of signal bearing medium used toactually carry out the distribution. Examples of a signal bearing mediuminclude the following: a recordable type medium such as a floppy disk, ahard disk drive, a Compact Disc (CD), a Digital Video Disk (DVD), adigital tape, a computer memory, etc.; and a transmission type mediumsuch as a digital and/or an analog communication medium (e.g., a fiberoptic cable, a waveguide, a wired communications link, a wirelesscommunication link (e.g., transmitter, receiver, transmission logic,reception logic, etc.).

The foregoing description of these aspects has been presented forpurposes of illustration and description. It is not intended to beexhaustive or limiting to the precise form disclosed. Modifications orvariations are possible in light of the above teachings. These aspectswere chosen and described in order to illustrate principles andpractical application to thereby enable one of ordinary skill in the artto utilize the aspects and with modifications as are suited to theparticular use contemplated. It is intended that the claims submittedherewith define the overall scope.

Various aspects of the subject matter described herein are set out inthe following numbered examples:

Example 1

A surgical instrument, comprising: a displacement member; a motorcoupled to the displacement member to translate the displacement member;a control circuit coupled to the motor; a position sensor coupled to thecontrol circuit, the position sensor configured to measure the positionof the displacement member and configured to measure an articulationangle of an end effector relative to a longitudinally extending shaft;wherein the control circuit is configured to: determine the articulationangle between the end effector and the shaft; select a force thresholdbased on the articulation angle; set motor velocity based on thearticulation angle; determine force on the displacement member; andadjust the motor velocity when the force on the displacement member isgreater than the force threshold.

Example 2

The surgical instrument of Example 1, wherein the control circuit isconfigured to determine actual position of the displacement member.

Example 3

The surgical instrument of Example 1 through Example 2, wherein thecontrol circuit is configured to determine end of firing stroke of thedisplacement member.

Example 4

The surgical instrument of Example 1 through Example 3, wherein thecontrol circuit is configured to compare the force on the displacementmember to the force threshold.

Example 5

The surgical instrument of Example 1 through Example 4, furthercomprising a timer/counter circuit coupled to the control circuit, thetimer/counter circuit configured to measure elapsed time; wherein thecontrol circuit is configured to: set the motor velocity; receive aninitial position of the displacement member from the position sensor;receive a reference time t.sub.1 from the timer/counter circuitcorresponding to the initial position of the displacement member; anddetermine an anticipated position of the displacement member at a timet.sub.2 based on the motor velocity.

Example 6

The surgical instrument of Example 5, wherein the control circuit isconfigured to: receive an actual position of the displacement member atthe time t.sub.2 from the position sensor; compare the actual positionof the displacement member at the time t.sub.2 with the anticipatedposition of the displacement member at the time t.sub.2; and determinethe force on the displacement member based on a difference between theactual position of the displacement member at the time t.sub.2 and theanticipated position of the displacement member at the time t.sub.2.

Example 7

The surgical instrument of Example 1 through Example 6, wherein thecontrol circuit is configured to lower the motor velocity until theforce on the displacement member is less than the force threshold.

Example 8

A surgical instrument, comprising: a displacement member; a motorcoupled to a proximal end of the displacement member to translate thedisplacement member; a control circuit coupled to the motor; a positionsensor coupled to the control circuit, the position sensor configured tomeasure a position of the displacement member relative to an endeffector and configured to measure an articulation angle of the endeffector relative to a longitudinally extending shaft; wherein thecontrol circuit is configured to: determine the articulation anglebetween the end effector and the longitudinally extending shaft; and setmotor velocity based on the articulation angle.

Example 9

The surgical instrument of Example 8, wherein the control circuit isconfigured to determine actual position of the displacement member.

Example 10

The surgical instrument of Example 8 through Example 9, wherein thecontrol circuit is configured to determine end of firing stroke of thedisplacement member.

Example 11

The surgical instrument of Example 8 through Example 10, wherein thecontrol circuit is configured to compare the articulation angle with aprevious articulation angle.

Example 12

The surgical instrument of Example 11, wherein the control circuit isconfigured to adjust the set motor velocity based on a new articulationangle.

Example 13

The surgical instrument of Example 8 through Example 12, furthercomprising a timer/counter circuit coupled to the control circuit, thetimer/counter circuit configured to measure elapsed time; wherein thecontrol circuit is configured to: set the motor velocity; receive aninitial position of the displacement member from the position sensor;receive a reference time t.sub.1 from the timer/counter circuitcorresponding to the initial position of the displacement member; anddetermine an anticipated position of the displacement member at a timet.sub.2 based on the set motor velocity.

Example 14

The surgical instrument of Example 13, wherein the control circuit isconfigured to: receive an actual position of the displacement member atthe time t.sub.2 from the position sensor; compare the actual positionof the displacement member at the time t.sub.2 with the anticipatedposition of the I-beam member at the time t.sub.2; and determine a forceon the displacement member based on a difference between the actualposition of the displacement member at the time t.sub.2 and theanticipated position of the displacement member at the time t.sub.2.

Example 15

A method of controlling motor velocity in a surgical instrument, thesurgical instrument comprising a displacement member, a motor coupled tothe displacement member to translate the displacement member, a controlcircuit coupled to the motor, and a position sensor coupled to thecontrol circuit, the position sensor configured to measure a position ofthe displacement member and configured to measure an articulation angleof an end effector relative to a longitudinally extending shaft, themethod comprising: determining, by the control circuit, an articulationangle between an end effector and a longitudinally extending shaft; andsetting, by the control circuit, motor velocity based on thearticulation angle.

Example 16

The method of Example 15, further comprising: selecting, by the controlcircuit, a force threshold based on the articulation angle; determining,by the control circuit, force on the displacement member; and adjusting,by the control circuit, the motor velocity when the force on thedisplacement member is greater than the force threshold.

Example 17

The method of Example 15 through Example 16, further comprisingdetermining, by the control circuit, actual position of the displacementmember.

Example 18

The method of Example 15 through Example 17, further comprisingdetermining, by the control circuit, end of firing stroke of thedisplacement member.

Example 19

The method of Example 15 through Example 18, further comprisingcomparing, by the control circuit, the articulation angle with aprevious articulation angle.

Example 20

The method of Example 19, further comprising adjusting, by the controlcircuit, the motor velocity based on a new articulation angle.

What is claimed is:
 1. A surgical instrument, comprising: a displacementmember; a motor coupled to the displacement member to translate thedisplacement member; a control circuit coupled to the motor; a positionsensor coupled to the control circuit, the position sensor configured tomeasure the position of the displacement member and configured tomeasure an articulation angle of an end effector relative to alongitudinally extending shaft; wherein the control circuit isconfigured to: determine the articulation angle between the end effectorand the shaft; select a force threshold based on the articulation angle;set motor velocity based on the articulation angle; determine force onthe displacement member; and adjust the motor velocity of the motor whenthe force on the displacement member is greater than the forcethreshold.
 2. The surgical instrument of claim 1, wherein the controlcircuit is configured to determine actual position of the displacementmember.
 3. The surgical instrument of claim 1, wherein the motor furthertranslates the displacement member during a firing stroke to deploystaples into tissue grasped by an end effector of the surgicalinstrument, and further wherein the control circuit is configured todetermine an end of the firing stroke of the displacement member.
 4. Thesurgical instrument of claim 1, wherein the control circuit isconfigured to compare the force on the displacement member to the forcethreshold.
 5. The surgical instrument of claim 1, further comprising atimer/counter circuit coupled to the control circuit, the timer/countercircuit configured to measure elapsed time; wherein the control circuitis configured to: set the motor velocity; receive an initial position ofthe displacement member from the position sensor; receive a referencetime t₁ from the timer/counter circuit corresponding to the initialposition of the displacement member; and determine an anticipatedposition of the displacement member at a time t₂ based on the motorvelocity.
 6. The surgical instrument of claim 5, wherein the controlcircuit is configured to: receive an actual position of the displacementmember at the time t₂ from the position sensor; compare the actualposition of the displacement member at the time t₂ with the anticipatedposition of the displacement member at the time t₂; and determine theforce on the displacement member based on a difference between theactual position of the displacement member at the time t₂ and theanticipated position of the displacement member at the time t₂.
 7. Thesurgical instrument of claim 1, wherein the control circuit isconfigured to lower the motor velocity until the force on thedisplacement member is less than the force threshold.
 8. The surgicalinstrument of claim 1, wherein the control circuit is configured to:select a force threshold based on the articulation angle; determineforce on the displacement member; and adjust the motor velocity when theforce on the displacement member is greater than the force threshold. 9.The surgical instrument of claim 1, wherein the control circuit isfurther to compare the articulation angle with a previous articulationangle and adjust the motor velocity based on a new articulation angle.10. The surgical instrument of claim 1, wherein the motor furthertranslates the displacement member during a firing stroke to deploystaples into tissue grasped by the end effector of the surgicalinstrument, and further wherein the control circuit is configured to:during the firing stroke, detect a change in the articulation anglebetween the end effector and the longitudinally extending shaft during atranslation of the displacement member to deploy staples into thetissue; during the firing stroke, cause the motor to adjust a velocityof the displacement member during the translation of the displacementmember to deploy staples into the tissue, wherein the adjustment of thevelocity of the displacement member is based on the change in thearticulation angle during the translation of the displacement member todeploy staples into the tissue; and determine if the displacement memberis at an end of the firing stroke.
 11. A method of controlling motorvelocity in a surgical instrument, the surgical instrument comprising adisplacement member, a motor coupled to the displacement member totranslate the displacement member, a control circuit coupled to themotor, and a position sensor coupled to the control circuit, theposition sensor configured to measure a position of the displacementmember and configured to measure an articulation angle of an endeffector relative to a longitudinally extending shaft, the methodcomprising: determining, by the control circuit, the articulation anglebetween the end effector and the shaft; selecting, by the controlcircuit, a force threshold based on the articulation angle; setting, bythe control circuit, motor velocity based on the articulation angle;determining, by the control circuit, force on the displacement member;and adjusting, by the control circuit, the motor velocity of the motorwhen the force on the displacement member is greater than the forcethreshold.
 12. The method of claim 11, further comprising determining,by the control circuit, an actual position of the displacement member.13. The method of claim 11, wherein the motor further translates thedisplacement member during a firing stroke to deploy staples into tissuegrasped by the end effector of the surgical instrument, the methodfurther comprising determining, by the control circuit, an end of thefiring stroke of the displacement member.
 14. The method of claim 11,further comprising comparing, by the control circuit, the force on thedisplacement member to the force threshold.
 15. The method of claim 11,further comprising a timer/counter circuit coupled to the controlcircuit, the timer/counter circuit configured to measure elapsed time;wherein the method further comprises: setting, by the control circuit,the motor velocity; receiving, by the control circuit, an initialposition of the displacement member from the position sensor; receiving,by the control circuit, a reference time t₁ from the timer/countercircuit corresponding to the initial position of the displacementmember; and determining, by the control circuit, an anticipated positionof the displacement member at a time t₂ based on the motor velocity. 16.The method of claim 15, further comprising: receiving, by the controlcircuit, an actual position of the displacement member at the time t₂from the position sensor; comparing, by the control circuit, the actualposition of the displacement member at the time t₂ with the anticipatedposition of the displacement member at the time t₂; and determining, bythe control circuit, the force on the displacement member based on adifference between the actual position of the displacement member at thetime t₂ and the anticipated position of the displacement member at thetime t₂.
 17. The method of claim 11, further comprising lowering, by thecontrol circuit, the motor velocity until the force on the displacementmember is less than the force threshold.
 18. The method of claim 11,further comprising: selecting, by the control circuit, a force thresholdbased on the articulation angle; determining, by the control circuit,force on the displacement member; and adjusting, by the control circuit,the motor velocity when the force on the displacement member is greaterthan the force threshold.
 19. The method of claim 11, further comprisingcomparing, by the control circuit, the articulation angle with aprevious articulation angle and adjusting the motor velocity based on anew articulation angle.
 20. The method of claim 11, wherein the motorfurther translates the displacement member during a firing stroke todeploy staples into tissue grasped by the end effector of the surgicalinstrument, and further wherein the method further comprises: during thefiring stroke, detecting, by the control circuit, a change in thearticulation angle between the end effector and the longitudinallyextending shaft during a translation of the displacement member todeploy staples into the tissue; during the firing stroke, causing, bythe control circuit, the motor to adjust a velocity of the displacementmember during the translation of the displacement member to deploystaples into the tissue, wherein the adjustment of the velocity of thedisplacement member is based on the change in the articulation angleduring the translation of the displacement member to deploy staples intothe tissue; and determining, by the control circuit, if the displacementmember is at an end of the firing stroke.
 21. A surgical instrument,comprising: a displacement member; a motor coupled to the displacementmember to translate the displacement member; a control circuit coupledto the motor; a first sensor coupled to the control circuit, theposition sensor configured to measure the position of the displacementmember; and a second sensor coupled to the control circuit, the secondsensor configured to measure an articulation angle of an end effectorrelative to a longitudinally extending shaft, wherein the controlcircuit is configured to: detect a change in the articulation anglebetween the end effector and the shaft; and adjust the motor velocity ofthe motor when a force on the displacement member is greater than aforce threshold selected based on the articulation angle.